Clot retrieval device for removing occlusive clot from a blood vessel

ABSTRACT

A clot retrieval device ( 9501 ) for removing occlusive clot from a blood vessel comprises an inner elongate body ( 9503 ) and an outer elongate body ( 9504 ) at least partially overlying the inner elongate body ( 9503 ). The device also comprises an elongate member or shaft ( 9502 ) having a proximal end which extends exterior of a patient so that a user can retrieve the stent-basket device and captured clot by retracting the shaft ( 9502 ). The outer elongate body ( 9504 ) and the inner elongate body ( 9503 ) are connected to the distal end of the shaft ( 9502 ) and are expandable relative to the shaft ( 9502 ) from a collapsed delivery configuration to an expanded deployed configuration. The outer elongate body ( 9504 ) is expandable relative to the inner elongate body ( 9503 ) to a radial extent which is greater than the radial extent of the inner body ( 9503 ) in the deployed configuration.

FIELD OF THE INVENTION

This invention relates to devices and methods of removing acuteblockages from blood vessels. The invention especially relates toremoving acute obstructions from blood vessels. Acute obstructions mayinclude clot, misplaced devices, migrated devices, large emboli and thelike. Thromboembolism occurs when part or all of a thrombus breaks awayfrom the blood vessel wall. This clot (now called an embolus) is thencarried in the direction of blood flow. An ischemic stroke may result ifthe clot lodges in the cerebral vasculature. A pulmonary embolism mayresult if the clot originates in the venous system or in the right sideof the heart and lodges in a pulmonary artery or branch thereof. Clotsmay also develop and block vessels locally without being released in theform of an embolus—this mechanism is common in the formation of coronaryblockages. The invention is particularly suited to removing clot fromcerebral arteries in patients suffering acute ischemic stroke (AIS),from coronary native or graft vessels in patients suffering frommyocardial infarction (MI), and from pulmonary arteries in patientssuffering from pulmonary embolism (PE).

BACKGROUND

There are significant challenges associated with designing clot removaldevices that can deliver high levels of performance. Firstly there are anumber of access challenges that make it difficult to deliver devices.In cases where access involves navigating the aortic arch (such ascoronary or cerebral blockages) the configuration of the arch in somepatients makes it difficult to position a guide catheter. Thesedifficult arch configurations are classified as either type 2 or type 3aortic arches with type 3 arches presenting the most difficulty. Thetortuousity challenge is even more severe in the arteries approachingthe brain. For example it is not unusual at the distal end of theinternal carotid artery that the device will have to navigate a vesselsegment with a 180° bend, a 90° bend and a 360° bend in quick successionover a few centimetres of vessel. In the case of pulmonary embolisms,access is through the venous system and then through the right atriumand ventricle of the heart. The right ventricular outflow tract andpulmonary arteries are delicate vessels that can easily be damaged byinflexible or high profile devices. For these reasons it is desirablethat the clot retrieval device be compatible with as low profile andflexible a guide catheter as possible.

Secondly, the vasculature in the area in which the clot may be lodged isoften fragile and delicate. For example neurovascular vessels are morefragile than similarly sized vessels in other parts of the body and arein a soft tissue bed. Excessive tensile forces applied on these vesselscould result in perforations and hemorrhage. Pulmonary vessels arelarger than those of the cerebral vasculature, but are also delicate innature, particularly those more distal vessels.

Thirdly the clot may comprise any of a range of morphologies andconsistencies. Long strands of softer clot material may tend to lodge atbifurcations or trifurcations, resulting in multiple vessels beingsimultaneously occluded over significant lengths. More mature andorganized clot material is likely to be less compressible than softerfresher clot, and under the action of blood pressure it may distend thecompliant vessel in which it is lodged. Furthermore the inventors havediscovered that the properties of the clot may be significantly changedby the action of the devices interacting with it. In particularcompression of blood clot causes dehydration of the clot and results ina dramatic increase in both clot stiffness and coefficient of friction.

The challenges described above need to be overcome for any devices toprovide a high level of success in removing clot and restoring flow.Existing devices do not adequately address these challenges,particularly those challenges associated with vessel trauma and clotproperties.

DISCUSSION OF PRIOR ART

Stent-like clot retrievers are being increasingly used to remove clotfrom cerebral vessels of acute stroke patients. These are self expandingdevices, similar in appearance to a stent attached to the end of a longshaft, and are advanced through a microcatheter and deployed across clotobstructions in order to trap and retrieve them. They rely on a pinningmechanism to grab the clot by trapping the clot between theself-expanding stent-like body and the vessel wall. This approach has anumber of disadvantages:

A stent-like clot retriever relies on its outward radial force (RF) toretain its grip on the clot. If the RF is too low the stent-like clotretriever will lose its grip on the clot, but if the RF is too high thestent-like clot retriever may damage the vessel wall and may require toomuch force to withdraw. Therefore stent-like clot retrievers that havesufficient radial force to deal with all clot types may cause vesseltrauma and serious patient injury, and stent-like clot retrievers thathave appropriate radial force to remain atraumatic may not be able toeffectively handle all clot types.

The stent-like clot retriever pinning mechanism tends to compress thetrapped clot. This compressive force will tend to dehydrate the clot,which in turn tends to increase its coefficient of friction, making itmore difficult to remove from the vessel.

Conventional Stent-like clot retriever designs do not retain theirexpanded shape very well when placed in tension in bends, due to themanner in which their strut elements are connected to one another. Thiscan result in a loss of grip on a clot as the stent-like clot retrieveris withdrawn proximally around a bend in a tortuous vessel, with thepotential escape of the captured clot. This occurs because the struts ofthe stent-like clot retriever are placed in tension when it isretracted. This tension is due to friction between the device and theblood vessel, and is increased if an additional load is applied loadsuch as that provided by a clot. In a bend the struts on the outside ofthe bend are placed in higher tension than those on the inside. In orderto attain the lowest possible energy state the outside surface of thestent moves towards the inside surface of the bend, which reduces thetension in the struts, but also reduces the expanded diameter of thestent-like clot retriever.

Another disadvantage with this approach is that it relies on pinning theclot between the stent-like clot retriever and the vessel wall and thusmay not restrain the clot effectively when passing a branch vessel orwhen passing into a vessel that is larger than the fully expandeddiameter of the stent-like clot retriever.

Pinning the clot between the stent-like clot retriever and the vesselwall in order to remove it from the vessel also results in high shearforces against the side of the clot as it is removed, potentiallyreleasing fragments which may lead to further blockages in the distalvasculature.

For many reasons including some or all of the above limitations it isoften necessary for a physician to make multiple passes with a clotretrieval device in order to fully remove an obstructive clot. Howevereach time a clot retrieval device is withdrawn the access to the targetsite is lost. Thus it is necessary to readvance a guidewire andmicrocatheter to access and recross the clot, and then remove theguidewire and advance the clot retrieval device through themicrocatheter. Navigating the guidewire and microcatheter to the clotcan take a considerable amount of time especially if the vessels aretortuous. This additional time and device manipulation all adds to therisks to which the patient is exposed.

STATEMENT OF THE INVENTION

The disclosed designs overcome the disadvantages of existing mechanicalthrombectomy solutions. The term “engager” is used below to describethat portion of the invention that is configured to engage with and gripthe clot, being generally deployed within the clot and engaging with it.Terms including “expandable body”, “elongate basket”, “engaging basket”and “stent basket” may also be used to describe this portion of thedevice. Where the clot retrieval device comprises a dual layerconstruction, the outer layer may be referred to as a stent-basket outeror outer member or outer tubular member or outer body or outer elongatebody; and the inner layer may be referred to as an inner tube or flowtube or inner tubular member or inner body or inner elongate body. Theshaft of the device may also be referred to as an elongate member orelongate shaft.

Designs are disclosed in which an engager portion of the device isconfigured to be expanded within an occlusive clot in a blood vessel sothat the expanding engager allows the clot to migrate into a receptionspace within the body of the engager as the engager expands. The engageris delivered through a catheter to the site of the occlusion and ispositioned within the clot. The engager is expandable at the site of theocclusion and starts to compress the clot as it is expanded. The engagersurface comprises inlet openings and the inlet openings allow the clotto ‘escape’ from compression by displacing a significant portion of theclot through the inlet openings in the wall of the engager. Because asignificant portion of the clot is urged through the inlet openings inthe engager this minimizes compression of the clot and hence minimizesthe resultant increase in the clot coefficient of friction. This alsoreduces the radial force on the vessel in the region of the clot whichmeans a lesser force is required to withdraw the captured clot, which inturn means less vessel trauma and less tension on the distal vascularbed. The device is configured such that the radial force of the deviceacts strongly at a small diameter to engage with and grip clot, but actssoftly at a larger diameter to gently contact the vessel wall are alsodisclosed. In some embodiments ‘first radial force elements’ and ‘secondradial force elements’ act in concert to provide a high radial force ata small diameter. At larger diameters said ‘first radial force elements’may provide little or no input to radial force with the result that thedevice has a high radial force at a small diameter but a surprisinglylow radial force at a large diameter. In another set of variants the‘first radial force elements’ may act in concert with the ‘second radialforce elements’ at a small diameter and act against the ‘second radialforce elements’ at a larger diameter.

Other embodiments for further reducing the device contact force with thevessel during clot retraction are also disclosed. These actuatabledesigns allow the user to selectively increase the radial force of theengager once it has been deployed across the clot in order to firmlyengage it with the clot, and then reduce the radial force again so thatthe device and clot can be safely withdrawn without causing trauma tothe vessels. The initial high radial force enables the engager to befirmly embedded in the clot and the clot to be effectively disengagedfrom the vessel. Once the clot is gripped and disengaged a high radialforce is no longer required, and a lower radial force can be used towithdraw the clot.

The engager interacts with the clot in two distinct phases of theretrieval process. Firstly the engager expands radially outward duringthe deployment phase and in doing so it compresses the clot somewhatagainst the vessel wall and urges at least some of the clot through thewall of the engager, especially the inlet openings. Secondly, during theremoval phase the engager acts on the clot in a direction substantiallyparallel to the longitudinal axis of the vessel. Urging the clot intowards the inside of the body of the engager has the added advantage ofallowing the engager struts to exert a force on the clot in a directionclose to or equal to the direction in which the clot is to be moved.With these embodiments portions of the clot straddle the wall of theengager. Thus when the engager is retracted proximally the straddledclot is unable to slide relative to the wall of the engager. In effectthe straddled clot is keyed to the engager during the withdrawal action.This in turn enables indentation or engagement features to be added tothe struts to further grip the clot even more securely.

Clot engagement features that enable the device to grip the clot withoutthe need for a high radial force are disclosed. These shaped clotengaging strut surfaces include eyelets, tabs and other shapesconfigured to impinge upon and project into the clot but not into thevessel wall. Also disclosed are surface modifications which provide alow coefficient of friction on one surface for vessel wall contact, anda higher coefficient of friction on strut sides and/or inner surfacesfor clot gripping. Clot engagement features generally increase the shearforces applied to the clot without increasing the radial force of thedevice. The engagement features may be configured to embed into theclot. The embedding of the engagement features means that it is moredifficult for a strut with clot engagement features to slide over theclot when the expanded device is withdrawn. Instead the embeddedengagement features apply a high shearing force which in the limit maytear a portion of the clot in the region of the engagement feature. Thehigh shear force transmitted to the clot by clot engagement featureswithout the need for high radial force makes this aspect of theinvention very attractive.

Designs with dual tubular members are disclosed whereby the engagercomprises a first inner expandable tube and a second outer expandabletube the inner tube being arranged substantially within the lumen of theouter tube. The properties of the inner tube and outer may be tailoredindependently of each other. The inner tube may have a very differentradial force to the outer tube. The inner tube may have a very differentlevel of porosity to the outer tube. The inner tube may have a fullyexpanded diameter that is very different to that of the outer tube. Thelength of the inner tube may be different to that of the outer tube. Theshape of the struts of the inner tube may be different to the shape ofthe struts of the outer tube. There may be a clearance between the innertube and the outer tube in the expanded configuration. There may be aclearance between the inner tube and the outer tube in the collapsedconfiguration. One, or both or neither of the inner and outer tubes mayhave a seam which runs substantially longitudinally along at least aportion of the wall of the tube. One, or both of the inner and outertubes may comprise a laser cut tube, a braided tube, a knitted tube, anextruded tube, a pultruded tube, One or both of the inner and outertubes may be manufactured with a process involving a laser cutting step,a braiding step, a knitting step, an extrusion step, a pultrusion step,an electropolishing step, a heat treatment step. One or both of theinner and outer tubes may comprise a tapered section, a flared section,a closed end section or a closed mid section.

These dual tube engagers have a number of benefits. (1) The inner tubecan be configured to provide a strong opening force to create a lumenthrough the clot and restore flow immediately on deployment. This flowlumen reduces the pressure gradient across the clot, making it easier toremove the clot. (2) The diameter to which the inner tube expands may betailored so as to reduce the risk of a reperfusion injury. With thisembodiment the inner tube expands to a diameter that is significantlysmaller than the diameter of the vessel immediately adjacent to anddistal of the occlusion. This small diameter inner tube creates a smallflow lumen across the occlusion and restricts the initial blood flow tothe affected portion of the brain. This restricted blood flow ensuresthat the pressure applied to blood vessels immediately after flowrestoration is lower than normal and this reduces the risk of bleedingin the ischemic vascular bed. Full perfusion is subsequently restored byremoving the device and the clot. (3) The inner tube may be configuredto expand to a lesser diameter than the outer basket and to a lesserdiameter than any vessel in which it is to be deployed. This means thata strong radial force may be safely exerted on the clot to open up aflow lumen, but need not be exerted on the vessel. (4) The inner tubecan serve to scaffold the lumen created through the clot, preventing theliberation of emboli from the clot into the resultant fast flowingbloodstream. (5) The inner tube may at least partially comprise a stentand can provide a strong grip on the clot for the critical initial stepof disengaging the clot from the vessel, enabling the outer basket to beconfigured with a low radial force. (6) The outer tube may be configuredto have large inlet openings so as to urge clot across the wall of theouter. The inner tube on the other hand may be configured to preventdistal migration or fragmentation or embolization of clot that traversesthe wall of the outer tube. By configuring the outer tube so as toencourage clot to traverse the wall of the outer tube the device canmore effectively disengage clot from the wall of the vessel while thedevice is also effective at preventing loss of clot material with aninner tube with a shape and substructure that provides scaffolding.

Shape retaining designs are disclosed which are configured in such a wayas to allow the engager to retain its expanded diameter and remain incontact with the vessel when moved around bends. Means for achievingthis include providing a) articulation points to allow the device tobend freely, b) discontinuities in the strut connectivity so thattension is not transmitted along the length of the engager around theoutside of a bend and c) proximal connections which allow the engager torotate and self align into its lowest energy state when moving throughtortuousity.

Features to protect against fragmentation and distal embolization aredisclosed including a variety of net designs and dual layer engagers,which serve to contain any fragments that might be released from themain body of clot. Variants in which an inner layer is provided withinthe engager are disclosed which have the added benefit of providing anunobstructed lumen through the engager and clot to facilitate theearliest possible provision of blood flow to the distal vasculature.These dual layer designs have the benefit of scaffolding the inner lumenof the engager and filtering out fragments. They also facilitate a veryspace efficient design in which there is minimal “parking space”required distal to the clot. Anti-fragmentation features are alsodisclosed that sit at the distal end of the engager, or distal of theengager. These include capture net designs that may be independentlymovable relative to the engager portion, or may be tethered to theengager portion, or may be integral to the engager portion. Thesefeatures, combined with the previously mentioned features that limit thegeneration of fragments in the first place, minimize the risk of distalembolization during the clot removal procedure.

This invention also discloses features that allow the removal of clotsthat are lodged in vessels without causing trauma to the vessels. In thecase of brain arteries which are very fragile and tortuous thesefeatures are extremely important. Where the device constructioncomprises an inner tube and an outer tube the outer tube may beconfigured as a low radial force structure that expands to a largediameter and the inner tube may be configured as a high radial forcestructure that expands to a small diameter. The device may be configuredsuch that the inner tube is protected from contact with the vessel wallas the device is retracted through the vasculature to the removal site.The low radial force outer tube does contact the vessel wall but sinceit has a low contact force it is very atraumatic to the vessel.

In one set of embodiments the distal end of the device is designed alsoto be very atraumatic so as to allow safe advancement of the device insmall tortuous fragile vessels. In the collapsed delivery configurationthe engager is advanced through the lumen of a microcatheter and thedistal end of the engager may be advanced distal of the micro catheterduring the deployment of the engager. The distal end of the engager mayhave a graduated stiffness transition so that it will prolapse ifadvanced against an artery wall in its collapsed or partially collapsedstate. In the expanded configuration the engager may comprise agenerally tapering and axially compressible distal section. The distalend of the engager may taper in a conical shape, or in a pyramidal shapeor it may comprise a ‘bullnose’ shape. This compressible distal sectionmay spread forces applied to the vessel wall across an increased area.The distal section may be configured such that advancement of theengager distal end against a wall results in a tactile feedback to theuser. The tactile feedback will alert the user to a potentialrestriction or resistance to device advancement and thus reduces thelikelihood of an inadvertent trauma to the vessel.

The features described above provide a high degree of recanalizationefficacy, so that clot may routinely be safely and easily removed in onepass. There may however be certain circumstances in which additionalpasses are desired. Designs are disclosed herein in which an accessplatform may be left in place after any device pass, over which the sameor another device may be quickly and easily readvanced.

In one embodiment of the invention the treatment apparatus comprises adevice for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member having a distal end, a proximal end and aproximal segment attached to the proximal end, wherein the distal endextends interior of the patient and the proximal end extends exterior ofthe patient. The expandable body is affixed adjacent the distal end ofthe elongate member and is delivered to the region of the occlusive clotthrough the lumen of a catheter in a collapsed configuration and ispositioned across the occlusive clot. The expandable body is deployed toan expanded configuration for engagement with the occlusive clot,wherein the expanded body comprising a plurality of struts configuredinto a tubular structure, the tubular structure comprising a first zoneand a second zone, wherein the first zone is configured to scaffold theclot outwardly against the vessel wall and the second zone comprises aplurality of openings in the wall of the expandable body, wherein theopenings configured to urge at least a portion of the occlusive clotthrough the wall of the tubular structure.

In another embodiment the treatment apparatus comprises a device forremoving an occlusive clot from a blood vessel, the device comprising anelongate member having a distal end and a proximal end, where the distalend extend interior of the patient and the proximal end extend exteriorof the patient, and, an expandable body affixed adjacent the distal endof the elongate member. The expandable is delivered to the region of theocclusive clot through the lumen of a catheter in a collapsedconfiguration and positioned across the occlusive clot and deployed tothe expanded configuration for engagement with the occlusive clot. Theexpandable body comprising an outer wall and an inner reception space,wherein the outer wall comprising a plurality of scaffolding sectionsand a plurality of inlet sections, wherein the scaffolding sections andinlet sections are configured to urge the occlusive clot into thereception space through the inlet sections.

In another embodiment of the invention the treatment apparatus comprisesa retrievable device for removing an occlusive clot from a blood vessel,the device comprising an elongate member having a distal end and aproximal end, wherein the distal end extend interior of the patient andthe proximal end extend exterior of the patient. An expandable body isaffixed adjacent the distal end of the elongate member and is deliveredto the region of the occlusive clot through the lumen of a catheter in acollapsed configuration and is positioned across the occlusive clot inan expanded configuration for engagement with the occlusive clot and theexpandable body comprises a clot engagement surface and a receptionspace. The device further comprises a capture net configured distal ofthe expandable body, delivered to the region of the occlusion clotthrough the catheter in a collapsed configuration and positioned distalof the occlusive clot in an expanded configuration to capture any clotfragments or emboli liberated by the action of the expandable body onthe occlusive clot, wherein the capture net comprises an expandableframe and a filtration net.

In another embodiment the therapy apparatus comprises a retrievabledevice for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member having a distal end and a proximal end,wherein the distal end extends interior of the patient and the proximalend extends exterior of the patient; and an expandable body affixedadjacent the distal end of the elongate member, delivered to the regionof the occlusive clot through the lumen of a catheter in a collapsedconfiguration and positioned across the occlusive clot in an expandedconfiguration for engagement with the occlusive clot, wherein theexpandable body comprises an outer tubular surface, a reception spaceand an inner tubular surface, wherein the outer tubular surface and theinner tubular surface are connected adjacent the proximal end of theexpandable body.

In another embodiment the device for removing an occlusive clot from ablood vessel comprises an elongate member having a distal end and aproximal end, wherein the distal end extend interior of the patient andthe proximal end extend exterior of the patient; and an expandable bodyaffixed adjacent the distal end of the elongate member, delivered to theregion of the occlusive clot through the lumen of a catheter in acollapsed configuration and positioned across the occlusive clot in anexpanded configuration for engagement with the occlusive clot, whereinthe expandable body comprising a tubular body comprising a firstsegment, a second segment, a third segment and a wall, wherein the firstsegment is configured to expand proximal of the occlusive clot toprevent movement of the occlusive clot in a proximal direction, whereinthe third segment is configured to expand distal of the occlusive clotto limit movement of the occlusion clot in a distal direction, whereinthe wall of the expandable body comprising regions of scaffolding andinlet openings wherein the regions of scaffolding are configured totransmit a pressure to the occlusive clot and inlet openings areconfigured to allow occlusive clot to extrude through the wall of theexpandable body.

In yet another embodiment of the invention the treatment apparatuscomprises a device for removing an occlusive clot from a blood vesselwherein the device comprises an elongate member having a distal end anda proximal end, wherein elongate member comprises a first elongateelement and a second elongate element; a first expandable body connectedto the first elongate element; and a second expandable body connected tothe second elongate element, wherein the second expandable body isspaced apart from distal end of the first expandable body.

In yet another embodiment of the invention the treatment apparatuscomprises a device for removing an occlusive clot from a blood vessel,the device further comprising an elongate member having a distal end, aproximal segment and a proximal end, wherein the distal end extendinterior of the patient and the proximal end extend exterior of thepatient; and an expandable body affixed adjacent the distal end of theelongate member, delivered to the region of the occlusive clot throughthe lumen of a microcatheter in a collapsed configuration and positionedacross the occlusive clot in an expanded configuration for engagementwith the occlusive clot, wherein the expandable body comprises at leasta first stent segment and a second stent segment, wherein first andsecond stent segments comprises a proximal end, a body section and adistal end, wherein the proximal end comprising an arrangement ofstruts, the body section comprising a tubular section configured todeliver a radial force and the distal end comprising at least oneterminal crown, wherein the second stent segment is spaced apart fromthe first stent segment and the distance between the first and secondstent segments defined by a connector strut.

In still another embodiment of the invention the treatment apparatuscomprises a device for removing an occlusive clot from a blood vessel,where the device comprises an elongate member having a distal end, aproximal segment and a proximal end, wherein the distal end extendsinterior of the patient and the proximal end extends exterior of thepatient; and an expandable body affixed adjacent the distal end of theelongate member, delivered to the region of the occlusive clot throughthe lumen of a microcatheter in a collapsed configuration and positionedacross the occlusive clot in an expanded configuration for engagementwith the occlusive clot, wherein the expandable body comprising aplurality of stent segments, wherein each stent segment comprising aproximal end, a body section and a distal end, wherein each stentsegment is spaced apart relative to other stent segment, wherein thestent segments comprising an inner lumen extending the length of theexpandable body, wherein the expandable body further comprises an innertube extending with the lumen, wherein the inner tube has a collapseddiameter and an expanded diameter, wherein the collapsed diameter issmaller than the inner diameter of the microcatheter and the expandeddiameter is larger than the outside diameter of the microcatheter,wherein the expanded diameter is smaller than the diameter of the bloodvessel.

In still another embodiment the treatment apparatus of the inventioncomprises a device for removing an occlusive clot from a blood vessel,the device further comprising an elongate member having a distal end, aproximal segment and a proximal end, wherein the distal end extendsinterior of the patient and the proximal end extends exterior of thepatient; and a stent-basket affixed adjacent the distal end of theelongate member, the stent basket delivered to the region of theocclusive clot through the lumen of a microcatheter in a collapsedconfiguration and positioned across the occlusive clot in an expandedconfiguration for engagement with the occlusive clot, wherein thestent-basket comprises a plurality of inlet openings, a reception space,a proximal section, a tubular body section and a distal section, whereinthe reception space is partially defined by the wall of the tubular bodysection, wherein at least one first inlet opening comprises a proximallyfacing inlet opening and at least one second inlet opening comprises anopening in the wall of the tubular body section.

Another treatment apparatus of the invention comprises a device removingan occlusive clot from a blood vessel, the device comprising an elongatemember having a distal end and a proximal end, wherein the distal endextends interior of the patient and the proximal end extends exterior ofthe patient; and an expandable body affixed adjacent the distal end ofthe elongate member, delivered to the region of the occlusive clotthrough the lumen of a microcatheter in a collapsed configuration andpositioned across the occlusive clot in an expanded configuration forengagement with the occlusive clot, wherein the expandable bodycomprising a plurality of struts configured into a tubular structure, avessel contacting surface, an inner surface, a distally facing surfaceand a proximally facing surface, wherein the vessel contacting surfacecomprising a surface with an RMS value of less than 0.25 microns,wherein at least a portion of the proximally facing surface comprisingat least one protrusion.

Another treatment apparatus of the invention comprises a device forremoving an occlusive clot from an occluded vessel, the devicecomprising an elongate member comprising an elongate tubular memberhaving a distal end and a proximal end, wherein the distal end extendsinterior of the patient and the proximal end extends exterior of thepatient; and an expandable body affixed adjacent the distal end of theelongate tubular member, delivered to the region of the occlusive clotthrough the lumen of a microcatheter in a collapsed configuration andpositioned across the occlusive clot in an expanded configuration forengagement with the occlusive clot, wherein the expandable bodycomprising a plurality of stent segments, wherein each stent segmentcomprises a proximal end, a body section, a distal end and a tubeelement, wherein the stent segments are spaced apart relative to eachother, wherein the proximal end comprising an arrangement of divergingstruts diverging from a tubular member, wherein the distal endcomprising an arrangement of converging struts, wherein the elongatemember further comprising a wire extending through the lumen of theelongate member, wherein the distal end of the wire configured to engagewith the distal end of the expandable body.

Yet another treatment apparatus of the invention comprises a device forremoving an occlusive clot from a blood vessel, the device comprising anelongate tube; an elongate wire, wherein the elongate wire and theelongate tube are coaxial and extend exterior of the patient; and anexpandable body delivered to the region of the occlusive clot throughthe lumen of a microcatheter in a collapsed configuration and positionedacross the occlusive clot in an expanded configuration for engagementwith the occlusive clot, wherein the expandable body is connected to thedistal end of the elongate tube at a primary attachment point and to thedistal end of the elongate wire at one or more secondary attachmentpoints, wherein the primary attachment point and secondary attachmentpoints are spaced apart, wherein the secondary attachment points aredistal of the primary attachment point, and in the expandedconfiguration relative movement of the elongate wire to the elongatetube transmits a force to the expandable body, wherein the force changesthe mechanical properties of the expandable body.

Another treatment apparatus of the invention comprises a device forremoving an occlusive clot from a blood vessel, the device comprising anelongate tube; an elongate wire, wherein the elongate wire and theelongate tube are coaxial and extend exterior of the patient; and anexpandable body delivered to the region of the occlusive clot throughthe lumen of a microcatheter in a collapsed configuration and positionedacross the occlusive clot in an expanded configuration for engagementwith the occlusive clot, wherein the expandable body comprising two ormore stent segments, wherein one of the stent segment comprises aproximal end, a mid section and a distal end, wherein the stent segmentis configured to expand by a relative movement of the elongate wirerelative to the elongate tube, wherein the relative movement assists theexpandable body in compressing at least a portion of the occlusive clot.

In another aspect of the invention the treatment apparatus comprises adevice for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member having a distal end and a proximal end,wherein the distal end extend interior of the patient and the proximalend extend exterior of the patient; and an expandable body affixedadjacent the distal end of the elongate member, delivered to the regionof the occlusive clot through the lumen of a microcatheter in acollapsed configuration and positioned across the occlusive clot in anexpanded configuration for engagement with the occlusive clot, whereinthe expandable body comprising an inner structure and an outerstructure, wherein the inner structure comprises an arrangement ofstruts configured to form a tube, wherein the outer structure comprisesa plurality of spaced apart ring members including a distal ring memberand a proximal ring member and at least two ring connectors, wherein thering connectors comprising a generally axially oriented memberconnecting adjacent ring members, wherein the ring connector extendingfrom the proximal ring member to the distal ring member, wherein thering connectors defining the distance between adjacent ring members,wherein the inner structure defines a lumen configured to facilitate theflow of blood from the proximal side of the occlusive clot to the distalend of the occlusive clot.

In yet another aspect of the invention the treatment apparatus comprisesa device for removing an occlusive clot from a blood vessel, the devicecomprising an elongate tube; an elongate wire, wherein the elongate wireand the elongate tube are coaxial and extend exterior of the patient;and an expandable body delivered to the region of the occlusive clotthrough the lumen of a microcatheter in a collapsed configuration andpositioned across the occlusive clot in an expanded configuration forengagement with the occlusive clot, wherein the expandable bodycomprises a tapered proximal end and a body section, wherein the bodysection comprises a plurality of struts arranged in a tubular structure,wherein the tubular structure comprises an inner lumen, wherein theelongate tube comprises a proximal end and a distal end, wherein theproximal end extends exterior of the patient and the distal end iscoupled to the tapered proximal end, wherein the elongate wire extendsdistal of the distal end of the elongate tube, wherein the elongate wirefurther extends through at least a portion of the inner lumen, whereinthe expandable body comprises at least one actuator strut, wherein theactuator strut extends from the body section radially inward and isconnected to the elongate wire, wherein the movement of the elongatewire relative to the elongate tube effects a change in the expandablebody.

In still another aspect of the invention the treatment apparatuscomprises a device for removing an occlusive clot from a blood vessel,the occlusive clot comprising a compressive body of material, whereinthe occlusive clot providing a resistance to compression, the bloodvessel comprising a distal vessel, a proximal vessel and an intermediatevessel, wherein the distal vessel comprises the site of occlusion, theproximal vessel comprises a vessel for removing the occlusive clot fromthe patient and the intermediate vessel comprises at least one curvedvessel segment, wherein the curved vessel segment has a central vesselaxis comprising a curved vessel axis, the device comprising, an elongatemember having a distal end, a proximal end and a proximal segment,wherein the distal end extend interior of the patient and the proximalsegment extend exterior of the patient; and an expandable body affixedadjacent the distal end of the elongate member, delivered to the regionof the occlusive clot through the lumen of a microcatheter in acollapsed configuration and positioned across the occlusive clot in anexpanded configuration for engagement with the occlusive clot, whereinthe expandable body comprising a length, wherein the length is greaterthan the radius of curvature of at least portion of the intermediatevessel, wherein the expandable body comprises a first tubular segmentand a second tubular segment, wherein the first tubular segmentcomprises a first central axis and the second tubular segment comprisesa second central axis, wherein the first central axis is substantiallytangential to a first part of the curved vessel axis and the secondcentral axis is tangential to a second part of the curved vessel axis,wherein the first tubular segment is connected to the second tubularsegment with an articulation, wherein articulation configured toarticulate the first tubular segment relative to the second tubularsegment while the expandable body passes through the curved vesselsegment.

In still another aspect of the invention the treatment apparatuscomprises a device for removing an occlusive clot from a blood vessel,the device comprising an elongate member having a distal end, a proximalend and a proximal segment attached to the proximal end, wherein thedistal end extend interior of the patient and the proximal extendexterior of the patient; and an expandable body affixed adjacent thedistal end of the elongate member, delivered to the region of theocclusive clot through the lumen of a catheter in a collapsedconfiguration and positioned across the occlusive clot in an expandedconfiguration for engagement with the occlusive clot, wherein theexpanded body comprising a skeleton structure of interconnected struts,wherein the skeleton structure comprising a tubular body with aplurality of inlet openings through the wall of the tubular body,wherein the inlet openings are configured to allow the ingress of theocclusive clot, wherein the tubular body defines at least one receptionspace with the lumen of the tubular body, wherein the occlusive clotmoving in the reception space through the inlet openings is preventedfrom migrating distally by at least one restraining layer arrangedacross the cross-section of the reception space, wherein the restraininglayer is configured to allow flow of blood and prevent the movement ofclot distally.

In still another aspect of the invention the treatment apparatuscomprises a device for removing occlusive clot from a blood vesselduring an endovascular procedure, the device comprising an elongate wireand an expandable body, the expandable body comprising a plurality ofrings wherein each ring comprises a collapsed state and an expandedstate and in the expanded state each ring comprises a plurality ofstruts and crowns connected in an alternating V shaped pattern, theexpandable body configured to grip the clot in the expanded state andconfigured to slide through a micro lumen in the collapsed state, theocclusive clot comprising a compressive body of material, said occlusiveclot resisting the expansion of the expandable body when the expandablebody is deployed within the occlusive clot, the expandable bodycomprising a plurality of first crowns and a plurality of second crownswherein the expansion force generated by a first crown is greater thanthe expansion force generated by a second crown.

In still another aspect of the invention the treatment apparatuscomprises a device for removing occlusive clot from a blood vesselduring an endovascular procedure, the device comprising an elongate wireand an expandable body, the elongate wire comprising a distal end, aproximal end and a proximal section the proximal section extendingexterior of the patient in use and the expandable body connected to theelongate wire adjacent the distal end of the elongate wire, theexpandable body comprising a plurality of rings wherein each ringcomprises a collapsed state and an expanded state, the rings furthercomprising a plurality of members, the expandable body configured togrip the clot in the expanded state and configured to slide through amicro lumen in the collapsed state, the occlusive clot comprising acompressive body of material, said occlusive clot resisting theexpansion of the expandable body when the expandable body is deployedwithin the occlusive clot, the expandable body comprising A regions andB regions whereby the cross-sectional area of members in the A regionsis greater than the cross-sectional area of members in the B regions,and the A regions and B regions are organised in a pattern.

Any of the above devices may be further configured in any of thefollowing ways:

The proximal segment of the device may be configured to extend thelength of the portion of the elongate member exterior of the patient. Inone embodiment the proximal segment is detachable. The elongate membermay comprise two or more elongate elements. In one embodiment at leastone elongate element is movable relative to the other elongate elementin a direction substantially parallel to the axis of the elongatemember. The device may comprise a capture net and the capture net may beattached adjacent the distal end of the movable elongate element. Themoveable elongate element may comprise a guidewire. The moveableelongate element may effect a change in the radial force of theexpandable body.

The expandable body affixed to the distal end of the elongate member maybe substantially concentric. The expandable body affixed to the distalend of the elongate member may be affixed substantially offset from thecentral axis. The expandable body may be a laser machined structure cutfrom a sheet or a tube. The expandable body may be an assembly ofmetallic wires. The expandable body may be self-expandable. Theexpandable body may be self-expandable by means of relative movement ofelongate elements. The tubular structure may be substantiallycylindrical. The tubular structure may comprise at least one taperedsection. The tapered section may taper distally. The tapered section maytaper proximally.

In one embodiment each strut comprises a section with a plurality ofclot indenting features. The clot indenting features may besubstantially proximally facing. The clot indenting features may beconfigured to project from the strut in a direction substantiallyparallel to the central axis of the tubular structure. In one embodimentthe openings of the second zone are greater than twice the size of thefirst zone.

The occlusion clot may comprise a hydrated state and in the hydratedstate the clot may occlude the vessel. The occlusive clot may furthercomprise a partially compressed dehydrated state and this state maycomprise the removal state. The inlet section may comprise an opening inthe outer wall of the expandable body. The scaffolding sections maycomprise a plurality of struts configured to appose the occlusive clot.The scaffolding section may cause at least a portion of the occlusiveclot to flow through the inlet section in the outer wall of theexpandable body as the expandable body expands.

When expanded in a 2 mm diameter vessel the scaffolding sections maycomprise a metal to artery ratio of greater than 1:15 and the inletsections may comprise a metal to artery ratio of less than 1:20. Theopenings of inlet sections may be greater than twice the size of theopenings in the scaffolding sections.

In one embodiment the inlet sections may comprise at least a first inletsection and a second inlet section. The first inlet section may belongitudinally spaced apart relative to the second inlet section. Thefirst inlet section may be circumferentially spaced apart relative tothe second inlet section. The reception space may comprise an enclosedreception space. The reception space may comprise a multiple of at leastpartially enclosed reception spaces.

The reception space may facilitate the passage of blood flow from theproximal end of the expandable body to the distal end of the expandablebody while filtering blood flow passing through the reception space. Theexpandable body may comprise a proximal inlet sized to facilitate bloodto flow into the reception space of the expandable body. The receptionspace may comprise a filtration wall.

In one embodiment the filtration wall prevents clot, clot fragments oremboli from passing through the reception space. The filtration wall maybe affixed to the distal region of the outer wall of the expandablebody.

The filtration wall and outer wall may in one embodiment substantiallydefine the reception space within the expandable body. The filtrationwall may be a braided structure, a knitted structure, a permeablemembrane, a porous metal wall or a laser cut tube. The filtration wallmay be a laser cut tube. The laser cut tube may comprise a parallelsection and a flared or funnel section. The filtration wall may be anexpandable wall. The expandable wall may be a self-expandable wall.

The elongate member may comprise two or more elongate elements. In yetanother embodiment at least one elongate element is movable relative tothe other elongate element in a direction substantially parallel to theaxis of the elongate member.

The filtration wall may be expandable by means of relative movement ofelongate elements. The filtration wall may be self-expandable which isoptionally assisted by means of relative movement of elongate elementsin expansion. The filtration wall may comprise a first end and a secondend. The first end may be attached to the elongate member and the secondend may be attached to the distal end of the expandable body.

In another embodiment the filtration wall comprises a plurality ofpores. In one embodiment the pores are not greater than 500 micrometers.In another embodiment the pores are not greater than 300 micrometers.

In one embodiment the elongate member has a circular outer circumferencecomprising a plurality of segments. The elongate member may comprise atleast one shaped helical element. The elongate member may furthercomprise at least one shaped helical metallic element. The elongatemember may be a laser cut metallic or polymeric tube or a braided tube.In one embodiment the elongate member comprises an inner wire and anouter elongate element. The outer elongate element may comprise a tubewith a low friction inner lumen. The outer elongate element may comprisea metallic tube with a low friction inner liner.

In one embodiment the capture net is attached to the inner wire and theexpandable body is attached to the outer elongate element. The elongatemember may comprise two or more elongate elements. The at least oneelongate element may be movable relative to the other elongate elementin a direction substantially parallel to the axis of the elongatemember. The capture net may be attached to one elongate element and theexpandable body may be attached to other elongate element. The capturenet may be attached to the expandable body. The capture net may beattached to the distal end of the expandable body by a flexible tether.The capture net may be attached by a connecting element to a pointadjacent the proximal end of the expandable body.

In one embodiment the expandable body may comprise an inner section andan outer section. The capture net may be attached to the inner section.The capture net may be attached to the outer section.

The expandable body may comprise a plurality of inlet ports configuredto facilitate occlusive clot to enter the reception space as theexpandable body expands. The expandable body may further comprise aplurality of interconnected struts arranged in an expandable pattern.The expandable frame may be configured to define a substantiallycircular opening. The expandable frame may be self-expandable.

The filtration net may comprise one or more fibres. The fibre may be apolymer or metallic monofilament. The fibre may be a polymer or ametallic multifilament. The fibre may comprise a nitinol, a stainlesssteel, an mp35N or a tungsten fibre. The fibre may comprise UHMWE,aramid, LCP, PET or PEN. The fibres may be connected to the expandableframe at discrete attachment points. The discrete attachment points maycomprise holes, slots, recesses or undulations in the expandable frame.At least a portion of the capture net is configured to sit within theexpandable body for delivery to the region of the occlusion clot.

In one embodiment the occlusive clot has a distal end, a proximal endand a material body. The outer tubular surface may be configured toextend from the proximal end of the clot to the distal end of the clot.The outer tubular surface may be configured to extend in the materialbody. The inner tubular surface may be configured to extend from theproximal end of the clot to the distal end of the clot. The innertubular surface may be configured to expand within the reception space.The diameter of the outer tubular surface may be larger than thediameter of the inner tubular surface in the expanded configuration. Theinner tubular surface may define a lumen through the device and theocclusive clot. The inner tubular surface may be a braided wire tube.The inner tubular surface may be a laser machined tube. The innertubular surface may be configured to provide a scaffolding surface.

In one embodiment the scaffolding surface may prevent migration of clotin the lumen. The inner tubular surface may have clot gripping features.The clot gripping features may be configured to project radiallyoutward. The clot gripping features may project substantiallyproximally. The clot gripping features may project both radially andproximally. The outer tubular surface may shield the vessel wall fromcontact with the inner tubular surface. The inner tubular surface may beconnected to the outer tubular surface at the distal end of the outertubular surface. The inner tubular surface may be connected to the outertubular surface adjacent to the distal end of the outer tubular surface.The radial force of inner tubular surface may be higher than that of theouter tubular surface. The radial force of inner tubular surface may belower than that of the outer tubular surface.

In another embodiment the outer tubular surface may comprise a matrix ofstrut elements. The strut elements may comprise strut sections with clotindenting features. The clot indenting features may be substantiallyproximally facing. The clot indenting features may be configured toproject from the strut elements in a direction substantially parallel tothe central axis of the outer tubular surface. The strut elements may beconfigured to define a plurality of openings to allow the occlusive clotto enter into the reception space.

In one variant the expandable body comprises a reception space withinthe tubular body. The reception space may comprise a closed distal end.The closed distal end may facilitate passage of blood flow. The closeddistal end may prevent passage of clot, fragments or emboli. Theexpandable body may comprise a nitinol body. The nitinol body may have aremembered expanded dimension equal to or greater than the diameter ofthe blood vessel diameter in the region of the occlusive clot. Thenitinol body may have a remembered expanded dimension equal to orgreater than the diameter of the blood vessel diameter proximal of theocclusive clot. The nitinol body may have a remembered expandeddimension equal to or greater than the diameter of the blood vesseldiameter distal of the occlusive clot. The wall may compriseinterconnected struts.

The interconnected struts may define one or more inlet mouths. Theinterconnected struts may define regions of clot scaffolding and regionsof clot reception.

In one embodiment the metal to artery ratio in the regions of clotscaffolding is more than twice that in the regions of reception. Theinterconnected struts may comprise clot gripping features. Some of theinterconnected struts may comprise clot gripping features.

The wall of an outer member may define the outer surface of thereception space. An inner tubular member may be located within thereception space. The inner tubular member may define a lumen through thereception space and the occlusive clot. The inner tubular member mayprevent fragments of occlusive clot entering the lumen. The innertubular member may be attached to a distal segment of the outer member.

In another embodiment the device further comprises a capture net. Thecapture net may be attached to a distal segment of the outer member. Thecapture net may be attached to the inner tubular member. The capture netmay be within the inner tubular member. The capture net may bepositioned distal of a distal segment of the outer member. Theexpandable body in the expanded configuration may apply a pressure onthe occlusive clot. In one embodiment the pressure is greater than thepressure in the reception space. In another embodiment the difference inpressures urge occlusive clot to flow through the inlet openings in theexpandable body.

In one variant the first elongate element is movable relative to thesecond elongate element. The first elongate element may be fixedrelative to the second elongate element. The first elongate element maybe a laser cut metallic or polymeric tube. The first elongate elementmay be a braided tube. The second elongate element may be a laser cut ormetallic or polymeric tube. The second elongate element may be a braidedtube. The first elongate element may be a tube with a low friction innerlumen. The second elongate element may be a metallic tube with a lowfriction inner liner. The second elongate element may comprise an innercable. The first expandable body may be configured to engage theocclusive clot. The second expandable body may be configured to captureany fragments released during removal of the occlusive clot.

The first expandable body may comprise a plurality of interconnectednitinol struts. The second expandable body may comprise a plurality ofnitinol struts and a net. The interconnected struts may beinterconnected with a plurality of connecting junctions. The connectionjunctions may comprise crowns or bifurcations. The interconnected strutsmay comprise a pattern. The interconnected struts may comprise at leastpartially a zig-zag pattern.

The arrangement of struts of the proximal end of the expandable body maycomprise a hoop. The hoop may be a distally sloping hoop. The distallysloping hoop may comprise a proximally facing surface and a distallyfacing surface. The proximally facing surface may comprise a smoothsurface. The distally facing surface may comprise at least one branchstrut. The body section may comprise a plurality of interconnectedstruts. The interconnected struts may be connected with a series ofjunction points. The junction points may comprise crowns or branchpoints.

The proximal end of the first stent segment of the expandable body maybe connected to the elongate member. The proximal end of the secondstent segment may be connected to the elongate member. The second stentsegment may be movable relative to the first stent segment. Theexpandable body may comprise more than two stent segments. The terminalcrown may not be directly connected to distal segment. The proximal endmay be configured to have a handle mounted over its outer diameter.

The device may further comprise a capture basket distal to theexpandable body. The capture basket may be configured to capture anyclot fragments or emboli liberated during the dislodgement and removalof the occlusive clot. The capture basket may comprise a proximalsegment, a middle segment and a distal segment. The proximal segment maycomprise at least one connector strut configured to connect the capturebasket to the elongate member. The middle segment may comprise anexpandable frame configured to self-expand and appose the wall of thevessel.

The distal segment may comprise a filtering surface. The filteringsurface may comprise a shaped surface. The filtering surface may beattached to the expandable frame at a plurality of connection points.The connection points may comprise a plurality of eyelets drilledthrough the wall of the expandable frame. The connection points may bearranged to allow the filtering surface extend across the entirecross-section of the vessel. The filtering surface may comprise aplurality of fibre segments fabricated into a porous filtering surface.The porous filtering surface may comprise a plurality of pores. At leasta portion of pores may have an opening of less than 500 micrometers. Thefiltering surface may comprise a braided surface or a knitted surface.

The expandable frame may comprise a plurality of nitinol struts. Thenitinol struts may be made from a tube using a laser machining process.The expandable body may further comprise at least one filter tube. Thefilter tube may comprise a generally tubular element with a plurality ofpores through the wall of the filter tube. The pores may be configuredto allow free movement of blood while filtering clot fragments or emboliparticles in the blood from passing distally. The filter tube may beconnected to the distal end of at least one stent segment. The filtertube may appose the wall of the vessel in the expanded configuration.The filter tube may comprise a plurality of filter members. The filtermembers may comprise at least one of a strut, a multifilament, afilament, a fibre, a yarn or a wire. The filter tube may comprise aclosed end. The filter members may be fixed together at the closed end.The closed end may be distal of the expandable body. The closed end maybe proximal of at least one stent segment. The closed end may beadjacent the proximal end of the expandable body.

The filter tube may comprise an expanded diameter. The expanded diametermay be smaller than the expanded diameter of stent segments over atleast a portion of the length of the filter tube.

In one variant the proximal end of each stent segment of the expandablebody comprises an arrangement of struts. The body section of each stentsegment may comprise a tubular section configured to deliver a radialforce. The distal end of each stent segment may comprise at least oneterminal crown. The inner tube may comprise a filter tube. The innertube may comprise a flared distal end. The flared distal end may befixed to the distal end of at least one stent segment. The inner tubemay comprise a plurality of fibres. The fibres may be fixed to thedistal end of at least one stent segment. The expandable body maycomprise a distal sac.

The stent-basket may comprise a plurality of interconnected struts. Theinterconnected struts may be connected by a plurality of connectionpoints. The connection points may comprise crown elements or strutsjunctions. At least one proximally facing inlet opening may comprise anopening in the proximal section. The opening may be defined by theproximal end of the tubular body section. The at least one proximallyfacing inlet opening may comprise a diameter. The diameter may bedefined by the diameter of the tubular body section.

The wall of the tubular body section may comprise a plurality ofinterconnected struts configured to scaffold clot outwardly. The devicemay further comprise at least one second inlet opening comprising aregion of the wall of the tubular body section without anyinterconnected struts. The region of the wall may comprise substantiallya quadrant of the circumference of the tubular body section.

The reception space may comprise an enclosed space. The occlusive clotmay enter the reception space through at least one of inlet opening. Theenclosed space may be defined by at least one reception space surface.The surface of the tubular body section may comprise a first receptionspace surface. The distal section may comprise a second reception spacesurface. The distal section and the tubular section may be joined tocreate a continuous reception space surface. The distal section and thetubular section may be integral.

The distal section may be configured to provide substantially noresistance while changing to the expanded configuration. The distalsection may be configured to provide substantially no resistance whileremoving the device. The distal section may comprise a net. Thereception space may be configured to facilitate entry of clot, fragmentsor emboli. The reception space may comprise a space to facilitate entryof clot, fragments or emboli. The entry of clot, fragments or emboli inthe space may be through at least one inlet opening. The clot, fragmentsor emboli may be prevented from escaping the reception space by thereception space surface comprising a porous surface. The reception spacesurface may comprise a plurality of struts. The reception space surfacemay comprise a net. The reception space surface may be defined by aplurality of wires or fibres.

The distal section may comprise a plurality of struts. The distalsection may comprise a plurality of wires or fibres. The stent-basketmay comprise a filter tube. The filter tube may be configured to allowblood to flow through the wall of the filter tube. The filter tube maybe configured to prevent clot fragments or emboli from passing throughthe filter tube. The filter tube may comprise a blood permeable surface.The filter tube may comprise a proximal end, a mid section and a distalend. The proximal end may comprise a connection point. The connectionpoint may be configured to connect the filter tube to the elongatemember.

The filter tube may be attached to the proximal end of stent-basket. Thefilter tube may be attached to the elongate member. The connection pointmay comprise a collar, a weld or an adhesive bond. The distal end of thefilter tube may comprise a dilated end or a trumpet shaped end. Thedistal end of the filter tube may comprise a distal rim. The distal rimmay be attached to the distal end of the tubular body section.

The vessel contacting surface of the expandable body may comprise asurface with an RMS value of less than 0.15 microns. The vesselcontacting surface may comprise a surface with an RMS value of less than0.10 microns. The protrusion may be configured to indent the occlusiveclot while the device is retracted from the vessel. The proximallyfacing surface of struts or rings of the expandable body may comprise asubstantially flat surface with one or more protrusions. The proximallyfacing surface may comprise a profiled surface with one or moreprotrusions comprising raised regions. The protrusion may comprise oneor more of a cylindrical segment, a spherical segment, a conicalsegment, a frustum, a triangular segment, a saw-tooth segment, aD-shaped segment, an eyelet element or a tab.

The vessel contacting surface may comprises a first edge and a secondedge. The first edge may comprise a transition between the vesselcontacting surface and the proximally facing surface. The second edgemay comprise a transition between the vessel contacting surface and thedistally facing surface. The first and second edges may comprise arounded edge. The rounded edge may comprise a radius of between 5microns and 35 microns. The rounded edge may comprise a radius ofbetween 10 microns and 25 microns. The rounded edge may comprise aradius of between 10 microns and 20 microns.

The proximally facing surface may comprise an inner segment and an outersegment. The inner segment comprises the portion of the proximallyfacing surface that is adjacent to the inner surface of the strut. Theouter segment may comprise a portion of the proximally facing surfacethat is adjacent to the vessel contacting surface of the strut. Theouter segment may comprise a smooth surface. The inner segment maycomprise at least one protrusion. The inner segment and outer segmentmay be integral.

The expandable body may comprise a vessel contacting configuration andthe projection may be configured such that in the vessel contactingconfiguration a clearance exists between the projection and the vesselwall.

The expandable body may comprise a super elastic metal or a shape memorymetal. The expandable body may comprise a polymeric material or aradiopaque metal. At least one of the struts of the expandable body maycomprise a first layer and a second layer.

The protrusion may be integral with the second layer. The vesselcontacting surface may comprise a hydrophilic coating. The proximallyfacing surface may comprise at least one recess. The proximally facingsurface may comprise a recess adjacent the junction between twointerconnected struts. The protrusion may comprise an eyelet. The eyeletmay facilitate the passage of a tether though the eyelet.

In the collapsed configuration the proximally facing surface of a firststrut may be configured to oppose the proximally facing surface of asecond strut. The first and second struts may be adjacent to each other.Protrusions of first and second struts may be arranged to nest together.

The diverging struts may comprise a plurality of struts diverging from atube, a ring member or a collar. The converging struts may comprise aplurality of struts converging from a tube, a ring member or a collar.The body section may comprise at least one expandable ring. Theexpandable ring may comprise a plurality of struts interconnected by aplurality of crowns and arranged in a zig-zag pattern.

The body section may be configured to engage with the occlusive clot.The body section may comprise an expanded diameter. The expandeddiameter may be greater than 50% of the diameter of the occluded vessel.The body section may comprise a fully expanded diameter. The fullyexpanded diameter may be substantially the same diameter of the occludedvessel. The expandable body may be configured for removal from thevasculature at a removal vessel through the lumen of a removal catheter.The removal vessel is proximal of the occluded vessel. The removalvessel is larger than the occluded vessel. The removal catheter is alarge lumen catheter. The fully expanded diameter of the expandable bodymay be substantially the same diameter of the removal vessel.

The diverging struts may be connected to the proximal end of the bodysection at a plurality of connection points. The connection points maycomprise a plurality of crown ends of the body section. The connectionpoints may comprise a plurality of Y shaped junctions. The convergingstruts may be connected to the proximal end of the body section at aplurality of connection points. The connection points may comprise aplurality of crown ends of the body section. The connection points maycomprise a plurality of U shaped junctions.

The stent segments may be moveable relative to each other. The wire mayextend through the lumen of the tube element. The wire may be slidablerelative to at least one distal end of the expandable body. The wire mayextend exterior of the patient and is capable of transmitting a pullforce from the user to the distal end of the expandable body.

The tube elements may comprise a proximal end, a distal end, at leastone proximal end and at least one distal end. The at least one distalend may comprise an abutment surface. The abutment surface may beconfigured to transmit a force from one tube element to adjacent tubeelement. The position of the plurality of tube elements associated withthe stent segments may be limited by the wire. The proximal end of thewire may be configured to allow the user to transmit a pull force to thedistal end of the wire.

The wire may comprise an engagement element adjacent the distal end. Theengagement element may facilitate the transmission of the pull forcefrom the wire to the tube element of a distal stent segment. The bodysection may be configured to transmit the pull force to the divergingstruts. The diverging struts may be configured to transmit the pullforce to the tube element. The most proximal tube element may beconfigured to transmit the pull force of the wire to the elongatetubular member. The pull force transmitted to the elongate tubularmember may comprise a reaction force substantially equal and opposite tothe pull force transmitted by the user.

The engagement element may comprise an abutment stop, a weld, anadhesive joint, a mechanical joint, a snap joint, a coupling, adetachable joint or a collar. The stent segments may comprise an innerlumen extending the length of the expandable body. The expandable bodymay further comprise an inner tube extending within the inner lumen ofthe stent segments. The inner tube may have a collapsed diameter and anexpanded diameter. The collapsed diameter of the inner tube may besmaller than the inner diameter of the microcatheter. The expandeddiameter is of the inner tube may be larger than the outside diameter ofthe microcatheter. The expanded diameter of the inner tube may besmaller than the diameter of the occluded vessel.

The pull force transmitted from the wire through the stent segments andthe reaction force of the elongate tubular member may effect anexpansion of the expandable body. The pull force transmitted from thewire through the stent segments and the reaction force of the elongatetubular member may effect an expansion of the body sections. The pullforce transmitted from the wire through the stent segments and thereaction force of the elongate tubular member may effect an increase inthe radial force of the expandable body.

The secondary attachment points between the expandable body and theelongate wire or actuation cable may comprise sliding connectionslimited by one or more stops on the elongate member. The secondaryattachment points may be fixedly attached to the expandable body.

The elongate wire may comprise a stop to limit the movement of theelongate wire relative to the elongate tube. The stop may be proximal ofthe secondary connections. The elongate wire may comprise a flexibletip. The elongate wire may comprise a formable tip. The change in themechanical properties may comprise an increase in the diameter of theexpandable body. The change in the mechanical properties may comprise anincrease in the radial force of the expandable body. The change in themechanical properties may comprise an increase in the resistance of theexpandable body to collapse while retracting the device.

The expandable body may comprise a tapered proximal end, parallel bodysection and a tapered distal end. The elongate tube may be attached tothe tapered proximal end. The elongate wire may be attached to thetapered distal end.

The expandable body may comprise a plurality of stent segments. Thestent segments may define one or more reception spaces. The stentsegments may be configured to provide one or more inlet openings toaccept the occlusive clot into the reception spaces. The stent segmentsmay be configured to provide one or more areas of scaffolding to urgethe occlusive clot into the reception spaces without dissecting theocclusive clot. The device may further comprise a capture net attachedadjacent the distal end of the expandable body.

The occlusive clot may comprise a compressive body of material. Theocclusive clot may provide a resistance to compression. The relativemovement may increases a radial force of at least a portion of theexpandable body. The relative movement may induce a displacement of atleast a portion of the occlusive clot. The displacement may occurwithout significant compression of the occlusive clot. The expandablebody may comprise a region of increased radial force and a region oflower radial force.

The relative movement may induce displacement of at least a portion ofthe occlusive clot from the region of increased radial force to theregion of lower radial force. The expandable body may comprise aplurality of struts. The struts may comprise a plurality of struts cutfrom a tube. The proximal end of stent segments may comprise a pluralityof struts and a point of divergence. The struts may extend distallysubstantially from the point of divergence. The proximal end of stentsegments may comprise a plurality of struts and a point of convergence.The struts may extend distally substantially towards the point ofconvergence. The point of divergence may comprise a point, a focal area,a ring, a collar or a circle. The divergence of struts may comprise aradial divergence. The point of convergence may comprise a point, afocal area, a ring, a collar or a circle. The convergence of struts maycomprise a radial convergence. The mid-section may comprise a pluralityof struts arranged in a ring structure.

The compression of the ring structure may induce an expansion of thering structure. The expandable body may extend proximally of the stentsegment. The expandable body may extend distally of the stent segment.The expandable body may extend proximally and distally of the stentsegment. The stent segments may be within the expandable body. The stentsegments may be moveable relative to the expandable body. The stentsegments may be integral with the expandable body.

The expandable body may comprise a body section. The body section maycomprise a tapered expandable body. The expandable body may furthercomprise a distal basket. The distal basket may be configured to capturethe occlusive clot fragments or emboli while allowing the passing ofblood.

The occlusive clot may comprise a compressive body of material. Theocclusive clot may provide a resistance to compression. The ring membersmay be configured to expand in the vessel to at least the diameter ofthe vessel. The ring members may be configured to appose the vessel wallaround substantially the entire circumference of the vessel. Theexpandable body may define an annual space between the outer structureand the tube.

The distance between the adjacent ring members may be configured to urgethe occlusive clot into the annular space while retracting. The ringmembers may be configured to engage the occlusive clot. The engagementmay comprise a local compression of the occlusive clot. The engagementmay comprise a local displacement of the occlusive clot. The engagementmay comprise a local compression of the occlusive clot and a localdisplacement of the occlusive clot.

The local displacement of the occlusive clot may urge at least a portionof the compressive body of material into the annular space. The annularspace may comprise a closed distal end. The closed distal end maycomprise a filtering structure. The filtering structure may allow thepassage of blood flowing distally from within the annular space. Thefiltering structure may prevent passage of the occlusive clot or clotparticles distally from within the annular space.

The filtering structure may comprise a net. The filtering structure maycomprise a mouth. The mouth may be substantially the same size ofdiameter of the distal ring member. The mouth may be fixed to the distalring member.

The filtering structure may comprise a capture space. The filteringstructure may be spaced apart from the distal ring member. The innerstructure may comprise a wall. The wall may comprise a porous wallconfigured to allow blood to flow through the wall. The porous wall mayprevent the movement of the occlusive clot or clot particles across thewall.

The inner structure may be configured to expand to a diameter smallerthan the diameter of the vessel. The inner structure may be configuredto expand to a diameter less than 80% of the diameter of the vessel. Theinner structure may be configured to expand to a diameter less than 60%of the diameter of the vessel. The inner structure may be configured toexpand to a diameter less than 40% of the diameter of the vessel. Theinner structure may be configured to expand to a diameter less than 30%of the diameter of the vessel. The inner structure may be configured toexpand to a diameter not greater than 2.5 mm. The inner structure may beconfigured to expand to a diameter not greater than 2.0 mm. The innerstructure may be configured to expand to a diameter not greater than 1.5mm. The inner structure may be configured to expand to a diameter notgreater than 1.0 mm.

The inner structure may comprise a stent. The inner structure maycomprise a covered stent. The inner structure may comprise a closed cellstent. The inner structure may comprise a stent with articulationregions. The inner structure may comprise a stent with terminal crowns.The inner structure may comprise a braided structure.

The ring members may comprise a plurality of hoops. The ring elementsmay comprise a plurality of hoops with a zig-zag pattern. The ringelements may comprise a plurality of hoops with regions of articulation.The regions of articulation may be equally spaced apart around thecircumference of each hoop. The ring connectors may be integral with thering members. The ring connectors may comprise a strut. The ringconnectors may be diametrically opposite on the outer structure. Thering connectors may be configured to articulate in tortuous anatomy.

The articulation of the ring connectors may be configured to allow thering members to appose the vessel wall in tortuous anatomy. The ringconnectors may comprise a connection junction with each ring member. Theconnection junction may comprise a “Psi” (ψ) shaped junction. Theconnection junction may comprise an X shaped junction.

The expandable body may comprise a proximal end. The proximal end maycomprise a tapered section. The tapered section may comprise a pluralityof sloping struts. The tapered section may comprise a plurality ofconverging struts. The region of convergence may be proximal. Thetapered section may comprise a plurality of struts connecting theelongate member and the outer structure. The tapered section maycomprise a plurality of struts connecting the elongate member and ringconnectors. The tapered section may comprise a plurality of strutsconnecting the elongate member and the proximal ring member. The taperedsection may comprise at least one strut connecting the elongate memberand the inner structure.

The body section of the expandable body may comprise a wall. A first endof the actuator strut may be integral with the wall. The expandable bodymay be configured to compress the occlusive clot laterally against thevessel wall. The expandable body may be configured to compress theocclusive clot to slide relative to the vessel wall.

The actuator strut may be coupled to the elongate wire. The actuatorstrut may extend radially inward into the inner lumen. The actuatorstrut may intersect with the elongate wire. The intersection maycomprise an acute angle and an obtuse angle. The acute angle maycomprise an angle of less than 60 degrees. The acute angle may comprisean angle of less than 45 degrees. The acute angle may comprise an angleof less than 30 degrees. The actuator strut may comprise a curvedportion. The curved portion may comprise a tangent with the elongatewire. The intersection may comprise a coupling. The coupling maycomprise an abutment, a collar, a bond, a joint, a weld or a connection.The coupling may comprise a sliding coupling. At least a portion of theelongate wire may be substantially coaxial of the inner lumen. At leasta portion of the elongate wire may be offset relative to the axis of theinner lumen. The actuator strut may comprise a pair of actuator struts.The pair of actuator struts may be diametrically opposed to each other.The pair of actuator struts may be placed equidistant from the distalend of the elongate tube. The pair of actuator struts may besubstantially of same length. The pair of actuator struts may be spacedapart along at least a portion of the length of the body section.

The body section of the expandable body may comprise at least one recessregion. The recess region may be defined by a plurality of struts in thebody section. The recess region may comprise a circumferential groove.The recess region may comprise a collar. The recess region may becoaxial with the body section. The recess region may be an eccentricrecession region.

The inner lumen defined by the expandable body may comprise a closedlumen. The inner lumen may comprise a reception space. The inner lumenmay comprise a substantially cylindrical space. The inner lumen maycomprise a substantially annular space. The tubular structure maycomprise a continuous cross-section. The tubular structure may comprisea non-continuous cross-section. The tubular structure may comprise a Cshaped tubular structure. The tubular structure may comprise a seam. Thetubular structure may comprise a first circular segment and a secondcircular segment. The first and second circular segments may overlapeach other. The first circular segment may comprise a first end face.The second circular segment may comprise a second end face. The firstend face and the second end face may overlap each other. The first endface and the second end face may be spaced apart. The first end face andthe second end face may extend at least a portion of the length of theexpandable body. The first end face and the second end face may extendsubstantially parallel to the axis of the expandable body. The first endface and the second end face may extend partially helically along theexpandable body.

The expandable body may comprise a plurality of struts. The struts maybe interconnected. The struts may be configured to appose the vesselwall by transmitting a radial force to the vessel wall.

The expandable body may comprise a compliant expandable body. Thecomplaint expandable body may be configured to appose the distal vessel,the proximal vessel and the intermediate vessel without causing traumato the vessel. The expandable body may comprise a biased configuration.The biased configuration may comprise the expanded state. During theexpanded state the axis of first tubular segment and the second tubularsegment may be substantially uniaxial. During the biased configurationthe first and second tubular segments may comprise a generally circularcross section.

The articulation of the device may be configured to absorb bendingforces applied to the expandable body by the curved vessel. Thearticulation may be configured to protect the first and second tubularsegments from bending forces applied to the expandable body by thecurved vessel. The expandable body may articulate to form a curvedconfiguration while moving from the curved vessel segment. In the curvedconfiguration the cross-section of the first and second tubular segmentsmay comprise a circular cross-section. The curved configuration maycomprise a neutral axis, an inner curve and an outer curve, and saidouter curve may be longer than the inner curve. The distance between theouter curve and the inner curve may be constant along the length of theexpandable body.

The articulation of the expandable body may comprise a connecting strut.The bending resistance of the connecting strut may be low compared tothe bending resistance of the first and second tubular segments. Theconnecting strut may comprise a first end and a second end. The firstend may be connected to the first tubular segment and the second end maybe connected to the second tubular segment.

The articulation of the expandable body may comprise two struts. Thebending resistance of two struts may be low compared to the bendingresistance of the first and second tubular segments. Said two struts maybe spaced apart around the circumference of the expandable body.

The articulation of the expandable body may comprise at least oneflexible connector.

The curved vessel segment may comprise a curve origin and a curve end.The curve origin may comprise an inflection point on the axis of thevessel. The curve end may comprise a second inflection point on the axisof the curved vessel segment. The curved vessel segment may comprise anangle of curvature. The angle of curvature may comprise an angle betweenthe inflection point and the second inflection point. The angle ofcurvature may be greater than 90 degrees. The angle of curvature may begreater than 135 degrees. The angle of curvature may be greater than 180degrees. The angle of curvature may be equal or less than 40 mm. Theangle of curvature may be equal or less than 30 mm. The angle ofcurvature may be equal or less than 20 mm. The angle of curvature may beequal or less than 15 mm. The angle of curvature may be equal or lessthan 10 mm. The angle of curvature may be equal or less than 7 mm. Thelength of the expandable body may be equal or greater than 8 mm. Thelength of the expandable body may be equal or greater than 10 mm. Thelength of the expandable body may be equal or greater than 15 mm. Thelength of the expandable body may be equal or greater than 20 mm. Thelength of the expandable body may be equal or greater than 30 mm. Thelength of the expandable body may be equal or greater than 40 mm. Thecurved vessel axis may comprise an irregular curve. The radius ofcurvature of the irregular curve may comprise a best fit circular curvebased on the data points between the points of inflection.

The expandable body may comprise a wall. The articulation may comprise acut-out section in the wall. The cut-out section may extend from oneside of the expandable body. The cut-out section may extend from twodiametrically opposite sides of the expandable body.

At least a portion of the previously mentioned skeleton structure of thedevice may extend distal of the occlusive clot. At least a portion ofthe skeleton structure may extend proximal of the occlusive clot. Theskeleton structure may comprise higher density scaffolding regions andlower density openings.

The inlet openings may be configured to allow easy passage of theocclusive clot into the reception space, may be configured to preventthe occlusive clot from escaping, may comprise a smooth inlet surface,may comprise a rough outlet surface, may comprise a low friction outersurface, and may comprise a high friction inner surface.

The vessel in which the device is used may comprise a distal vessel anda proximal vessel. The distal vessel may comprise the site of occlusion.The proximal vessel may comprise a vessel for removing the occlusiveclot from the patient.

The previously mentioned restraining layer may be a mesh layer, may begenerally tapering distally inward, may be generally tapering proximallyinward, may comprise strut elements. Said strut elements may beconnected to the elongate member. Said strut elements may be actuated toadjust the radial force of the expandable body. The distal restraininglayer may comprise a capture net.

Each crown of the expandable body may comprise a crown angle and in thecollapsed state the crown angle may be smaller than in the expandedstate. Each crown may comprise a crown angle and in the collapsed statethe crown angle may be between 0 degrees and 30 degrees and in theexpanded state the crown angle is greater than 30 degrees. In theexpandable body collapsed state the struts attached to each crown may besubstantially parallel, and in the expandable body expanded state thestruts attached to each crown may have moved apart to form a V shapedangle.

The expansion of the expandable body may comprise a first stage ofexpansion and a second stage of expansion. The first stage of expansionmay comprise compression of the occlusive clot by the expandable body.The first stage of expansion may comprise a high force opening of thefirst crowns. During the first stage of expansion the second crowns mayremain substantially collapsed. The second stage of expansion maycomprise a low force opening to a larger diameter. During the secondstage of expansion the second crowns may expand. During the second stageof expansion the change in the crown angle of the second crowns may besignificant. During the second stage of expansion the change in thecrown angle of the first crowns may be small relative to the crown anglechange associated with the second crowns.

The rings of the expandable body may comprise a first ring end and asecond ring end. The first ring end may comprise a plurality of firstcrowns and the second ring end may comprise a plurality of secondcrowns. The first ring end may comprise a plurality of crowns and saidplurality of crowns may comprise at least one first crown and at leastone second crown. The first ring end may comprise a plurality of crownsand said plurality of crowns may comprise at least one first crown andat least one second crown arranged in an alternating pattern.

The plurality of rings of the expandable body may comprise a first strutand a second strut and said first and second struts may be arranged in apattern. The first strut may comprise a greater cross-sectional areathan the second strut. The first strut may comprise a higher bendingstiffness than the second strut. The plurality of struts may comprise atleast one tapered strut. The plurality of struts may comprise at leastone strut with a first strut section and a second strut section and thewidth of the strut in the first strut section may be greater than thewidth in the second strut section.

The crowns of the expandable body may comprise spring elements and eachspring element may comprise a spring constant and the spring constant ofthe spring element of the first crown may be greater than the springconstant of the string element of the second crown.

At least one ring of the expandable body may comprise a partiallyexpanded state whereby the first crowns are at least partially expandedand the second crowns are substantially collapsed. The expandable bodymay be biased towards the expanded state.

The micro lumen may comprise the lumen of a catheter. The micro lumenmay comprise a lumen of 2.5 French or less.

The pattern in which the previously mentioned A regions and B regionsare organized may comprise an alternating pattern around thecircumference of at least one ring. The pattern may comprise A regionsat one end of a ring and B regions at the other end of a ring. Themembers may comprise struts, crowns, portions of struts, and portions ofcrowns. The expandable body may comprise a transition region between themembers. The transition region may comprise a tapered section. Themembers may comprise tapered elements. The cross-sectional area of atleast one member changes along the length of the member. A plurality ofadjacent members may define a cell and in the partially expanded statethe area of a cell comprising an A region may be greater than the areaof a cell of a B region.

At least one ring member of the expandable body may comprise radiopaquemarkers, and said radiopaque markers may be fixed to a crown of thering. The marker may be integral with the crown.

A method for removing an occlusive clot from a blood vessel is alsodisclosed, wherein the site of occlusion in the blood vessel comprises abifurcation region comprising a first branch vessel and a second branchvessel and a proximal vessel, wherein a portion of the occlusive clotextends into the first branch vessel and a portion of the occlusive clotextends into the second branch vessel, the method comprising steps ofproviding a device comprising an elongate member, an expandablestent-basket and an expandable distal capture net; advancing amicrocatheter and a guidewire across the occlusive clot, wherein thedistal end of the microcatheter extends into the lumen of the firstbranch vessel; advancing the device through the lumen of themicrocatheter across the occlusive clot; retracting the microcatheter;expanding the distal capture net distal of the occlusive clot; expandingthe expandable stent-basket within the occlusive clot; retracting theexpandable stent-basket; dislodging the occlusive clot from thebifurcation region; holding the dislodged occlusive clot in the proximalvessel and simultaneously retracting the distal capture net proximal ofthe bifurcation region; retracting the stent-basket into the distallumen of a guide catheter while simultaneously aspirating through thelumen of the guide catheter; and retracting the capture net into thelumen of the guide catheter.

Also disclosed is another method for removing an occlusive clot from ablood vessel wherein the occlusive clot comprises a compressive body ofmaterial and provides a resistance to compression. This method comprisesthe steps of providing a device comprising an elongate tube, an elongatewire, an expandable stent and an expandable distal capture net, whereinthe elongate tube is connected to the expandable stent and the elongatewire is connected to the capture net, wherein the elongate tube and theelongate wire are coaxial over at a least a portion of the length of theelongate tube. Then advancing a microcatheter and a guidewire across theocclusive clot; advancing the capture net and the stent through thelumen of the microcatheter across the occlusive clot; expanding thecapture net distal to the occlusive clot by retracting the microcatheterrelative to the capture net; expanding the stent within the occlusiveclot by retracting the microcatheter relative to the stent; capturingany liberated fragments or emboli with the capture net; sliding theelongate tube proximally relative to the elongate wire while holding theelongate wire substantially steadfast; withdrawing the stent to aproximal vessel; and retrieving the stent along with occlusive clot intothe lumen of a recovery catheter.

Also disclosed is another method for removing an occlusive clot from ablood vessel wherein the occlusive clot comprises a compressive body ofmaterial and provides a resistance to compression. This occlusive clotmay comprise a first part and a second part, and the method comprisesthe steps of providing a device comprising an elongate tube, an elongatewire, an expandable stent and an expandable distal capture net, whereinthe elongate tube is connected to the stent and the elongate wire isconnected to the capture net and wherein the elongate tube and elongatewire are coaxial over at least a portion of the length of the elongatetube. Then advancing the capture net and the stent in a collapsedconfiguration through the lumen of a microcatheter across the occlusiveclot; expanding the capture net distal to the occlusive clot byretracting the microcatheter relative to the capture net; expanding thestent within the occlusive clot by retracting the microcatheter relativeto the stent; sliding the elongate tube proximally while holding theelongate wire substantially steadfast; withdrawing the stent along thefirst part of the occlusive clot; engaging the proximal end of the stentwith the mouth of a recovering catheter; collapsing the stent byretracting the elongate tube while simultaneously aspirating through thelumen of the recovering catheter; and removing the stent along the firstpart of the occlusive clot from the patient.

For any of these methods the step of retracting the stent-basket mayfurther comprise the step of capturing clot fragments liberated by thestent-basket.

The step of expanding the stent-basket may comprise urging at least aportion of the occlusive clot into the stent-basket.

The step of dislodging the occlusive clot may comprise urging at least aportion of the occlusive clot into the stent-basket.

The device may be advanced through the lumen of the microcatheter in acollapsed configuration.

The stent-basket may be self-expanding by retracting the microcatheter.

The step of dislodging the occlusive clot may comprise a step ofcompressing the occlusive clot normal to the axis of the vessel.

The step of dislodging the occlusive clot may comprise a step ofdilating a flow lumen through the occlusive clot inside thestent-basket.

The step of retracting the stent-basket may comprise a step ofsimultaneous retraction of the capture net.

The guide catheter may comprise a flow limiting expandable collar.

The method may comprise a step of removing the guidewire from the lumenof the microcatheter, advancing the stent basket and the capture net ina collapsed configuration, visualizing the position of the basket andthe stent using a fluoroscope and adjusting the position of the basketand the stent relative to the occlusive clot.

The method may comprise a step of retracting the elongate wire relativeto the elongate tube and withdrawing the basket into the proximalvessel.

The method may comprise a step of retracting the elongate wire relativeto the mouth of the recovering catheter.

The step of expanding the stent may comprise a step of compressing atleast a portion of the occlusive clot, or may comprise a step ofdisplacing at least a portion of the occlusive clot. The method mayfurther comprise a step of providing the stent with at least one recessand the step of expanding the stent may comprise a step of displacing atleast a portion of the occlusive clot into the recess.

The method may comprise a step of removing the occlusive clot from arecovering catheter and aspirating the lumen of the recovering catheter.

The method may comprise a step of retracting the stent basket into thedistal lumen of the guide catheter while simultaneously aspiratingthrough the lumen of the guide catheter.

The method may comprise a step of advancing a microcatheter over theshaft of the elongate wire of the device.

The method of use may comprise a step of providing a second expandablestent, a second elongate tube and a second microcatheter, and saidsecond expandable stent, a second elongate tube and the secondmicrocatheter may be advanced through the lumen of the guide catheter,and over the shaft of the elongate wire. The method may further comprisea step of crossing a second part of the occlusive clot with the secondexpandable stent, the second elongate tube and the second microcatheterand expanding the second expandable stent within the second part of theocclusive clot by retracting the second microcatheter relative to thesecond expandable stent. The method of use may comprise a step ofsliding the second elongate tube proximally and disengaging the secondpart of the occlusive clot from the vessel wall, then sliding the secondelongate tube proximally and withdrawing the second expandable stentalong with second part of the occlusive clot to the proximal vessel, andthen engaging the proximal end of the second expandable stent with themouth of the recovery catheter. It may further comprise a step ofcollapsing the second expandable stent by retracting the elongate tubewhile simultaneously aspirating through the lumen of the recoverycatheter, and may further comprise a step of removing the secondexpandable stent along with the second part of the occlusive clot fromthe patient. The second expandable stent, second elongate tube andsecond microcatheter may actually be a second use of the stent, theelongate tube and the microcatheter.

The method may further comprise a step of engaging the proximal end ofthe capture net with the mouth of recovery catheter and collapsing thecapture net by retracting the elongate wire while simultaneouslyaspirating through the lumen of the recovery catheter and then removingthe second part of the occlusive clot from the patient.

In another embodiment of the invention the treatment apparatus comprisesa device for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member and a clot engaging structure, theelongate member configured to advance or retract the clot engagingstructure in a blood vessel, the clot engaging structure comprising aplurality of strut members the engaging structure further comprising anouter tubular sub-structure and an inner tubular substructure, the outertubular sub-structure configured to self-expand to a first diameter andthe inner tubular substructure configured to self-expand to a seconddiameter.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The first diameter is greater than the second diameter.    -   The first diameter is at least as big as the diameter of the        occluded vessel segment.    -   The first diameter is larger than the diameter of the occluded        vessel segment.    -   The second diameter is smaller than the diameter of the occluded        vessel segment.    -   The second diameter is between 20% and 60% of the diameter of        the occluded vessel.    -   The strut members of the inner tubular sub-structure are        arranged so as to provide a tubular clot scaffolding structure,        said tubular clot scaffolding structure comprising a plurality        of strut members and a plurality of interstices between adjacent        strut members and said strut members and interstices are        arranged so as to prevent clot material from the occlusive clot        from passing through the interstices of the inner tubular        sub-structure, the interstices providing minimal restriction to        the passage of blood across the wall of the inner tubular        sub-structure.    -   The inner tubular sub-structure extends substantially the length        of the occluded segment in the deployed configuration.    -   The clot engaging structure comprises a radial force, the radial        force varying with the diameter of the clot engaging structure        as the clot engaging structure expands.    -   The radial force of the clot engaging structure comprises a        combination of the radial force of the inner tubular structure        and the outer tubular structure.    -   The radial force the inner tubular structure is greater than the        radial force of the outer tubular structure when measured at        diameters of less than 90% of the fully expanded diameter of the        inner tubular member.    -   The radial force the inner tubular structure is greater than the        radial force of the outer tubular structure when measured at a        diameter of 90% of the fully expanded diameter of the inner        tubular member.    -   The radial force the inner tubular structure is greater than the        radial force of the outer tubular structure when measured at a        diameter of 70% of the fully expanded diameter of the inner        tubular member.    -   The radial force of the inner tubular structure is greater than        the radial force of the outer tubular structure when measured at        a diameter of 50% of the fully expanded diameter of the inner        tubular member.    -   The radial force the inner tubular structure is greater than the        radial force of the outer tubular structure when measured at a        diameter of 30% or less of the fully expanded diameter of the        inner tubular member.    -   The elongate member comprises a distal end and a proximal end,        the proximal end extending exterior of the patient, the distal        end comprising at least one substructure attachment point.    -   The at least one substructure attachment point is adjacent the        proximal end of the at least one substructure.    -   The inner tubular substructure comprises a first longitudinal        axis and the outer tubular substructure comprises a second        longitudinal axis the first and second longitudinal axes being        substantially parallel in the expanded state.    -   The first longitudinal axis can be displaced laterally relative        to the second longitudinal axis by forces exerted on either the        outer tubular substructure or the inner tubular structure by the        clot or the vessel.    -   The outer tubular substructure comprises at least one inlet        opening, said inlet opening configured to allow at least a        significant portion of the occlusive clot to pass through the        inlet opening.    -   The outer tubular substructure comprises at least one closed        cross-section. The at least one closed cross-section comprises a        wall of porous material across the diameter of the outer tubular        substructure. The at least one closed cross-section comprises a        plurality of struts and a plurality of interstices between said        struts. The at least one closed cross-section comprises a porous        mesh. The at least one closed cross-section is located at the        distal end of the outer substructure.    -   The inner tubular substructure is configured so as to provide a        closed cross-section.

In another embodiment of the invention the treatment apparatus comprisesa device for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member having a distal end, a proximal end and aproximal segment, wherein the distal end extends interior of a patientvasculature and the proximal end extends exterior of the patient; and anexpandable body affixed adjacent the distal end of the elongate member,the expandable body comprising a collapsed configuration for deliverythrough the lumen of a micro-catheter and an expanded configuration, theexpandable body biased towards the expanded configuration when notconstrained by the micro-catheter, the expandable body being furtherconfigured for deployment in an occluded segment of the vessel such thatthe expandable device extends across a substantial portion of theocclusive clot, the expandable body comprising a plurality of struts andsaid plurality of struts defining a cylindrical wall and said wallcomprising clot scaffolding regions and inlet holes wherein thedistribution of metal in the scaffolding regions is such that thescaffolding region will compress clot as it expands and the size andshape of the inlet holes is such that the inlet holes offer minimalresistance to the migration of clot through the inlet holes.

In yet another embodiment of the invention the treatment apparatuscomprises a self-expanding device for disengaging occlusive clot from ablood vessel in a patient, the occlusive clot comprising a body ofcompressible material including a fibrin content in excess of 2% and ablood fluids content in excess of 30%, the device comprising a pluralityof struts and said plurality of struts defining a cylindrical wall andsaid cylindrical wall extending longitudinally such that in its expandedstate the cylindrical wall prevents substantial axial migration of theclot relative to the device, the cylindrical wall further comprisingclot scaffolding regions and inlet holes wherein the distribution ofstrut material in the scaffolding regions is such that the scaffoldingregion will compress clot as the cylindrical wall expands and the sizeand shape of the inlet holes is such that the inlet holes offer minimalresistance to the migration of clot material through the inlet holes.

In certain embodiments of the above devices and of other devices of thisinvention:

-   -   The distal end of the cylindrical wall extends distal of the        occlusive clot and the proximal end of the cylindrical wall        extends proximal of the clot when the cylindrical wall is        expanded in the blood vessel.    -   In the expanded state at least a significant portion of the clot        has migrated through the inlet holes.    -   The distribution of strut material in the scaffolding regions is        such that when the device is expanded to a diameter of 3 mm the        maximum diameter sphere that could pass through a scaffolded        region without contacting the struts of the device is less than        2.5 mm.

In another embodiment of the invention the treatment apparatus comprisesa device for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member and a clot engaging structure, theelongate member configured to advance or retract the clot engagingstructure in a blood vessel; the clot engaging structure comprising anexpanded state and a collapsed state and a plurality of strut members,the clot engaging substructure further comprising an outer tubularsub-structure and an inner tubular substructure, the outer tubularsubstructure comprising an elongate body with an inner lumen and theinner tubular substructure being substantially within the lumen of theouter tubular substructure; the elongate body of the outer tubularsub-structure comprising a body section and a distal section, saidsections comprising a plurality of struts, said struts having a crosssection with a width and a thickness, wherein the thickness of one ormore of the struts in the distal section is lower than the thickness ofone or more of the struts in the proximal section.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   Both the width and thickness of one or more of the struts in the        distal section of the elongate body of the outer tubular        sub-structure are lower than both the both the width and        thickness of one or more of the struts in the proximal section    -   Both the width and thickness of one or more of the struts in the        distal section of the elongate body of the outer tubular        sub-structure are lower than both the both the width and        thickness of any of the struts in the proximal section    -   The inner tubular substructure is connected to the proximal end        of the outer tubular substructure.    -   The inner tubular substructure is connected to both the proximal        and distal ends of the outer tubular substructure.

In another embodiment of the invention the treatment apparatus comprisesa device for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member and a clot engaging structure, theelongate member configured to advance or retract the clot engagingstructure in a blood vessel, the clot engaging structure comprising anexpanded state and a collapsed state and a plurality of strut members,the clot engaging substructure further comprising an outer tubularsub-structure and an inner tubular substructure, the outer tubularsubstructure comprising an inner lumen and the inner tubularsubstructure being substantially within the lumen of the outer tubularsubstructure, the inner tubular sub-structure being laser machined froma first tube and the outer tubular structure being laser machined from asecond tube, the outer diameter of the first tube being smaller than theouter diameter of the second tube.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The second tube comprises an inner diameter and the outer        diameter of the first tube is smaller than the inner diameter of        the second tube.    -   The clot engaging structure comprises a collapsed delivery        configuration and an expanded deployed configuration.    -   The inner tubular substructure is substantially within the lumen        of the outer tubular substructure in the collapsed state.

In another embodiment of the invention the treatment apparatus comprisesa device for removing an occlusive clot from a blood vessel, the devicecomprising an elongate member and a clot engaging structure, theelongate member configured to advance or retract the clot engagingstructure in a blood vessel, the clot engaging structure comprising anexpanded state and a collapsed state and a plurality of strut members,the clot engaging structure further comprising an outer tubularsub-structure and an inner tubular substructure, the outer tubularsubstructure comprising an inner lumen and the inner tubularsubstructure being substantially within the lumen of the outer tubularsubstructure, the inner tubular sub-structure comprising a plurality oflongitudinal struts each strut comprising a length, said plurality ofstruts defining a porous tube, each strut comprising a first surface, asecond surface and a third surface, wherein the first surface comprisesan outer surface and the second and third surfaces have substantiallythe same width, and the second and third surfaces are disposed at anangle to each other whereby the angle is less than 90 degrees.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   Each of the first surface, the second surface and the third        surface comprises a region of intersection and said region of        intersection comprises a fillet.    -   The width of the second and third surfaces may be less than 80        micrometers.

In another embodiment of the invention the treatment apparatus comprisesa removable expandable device for use in the treatment of a patient withan occlusive clot in a blood vessel, the device comprising an elongatewire and an expandable body, the elongate wire configured such that whenthe expandable body is at the site of the occlusion the elongate wireextends exterior of the patient, the expandable body comprising aplurality of rings wherein each ring comprises a collapsed state and anexpanded state and each ring further comprises a plurality ofsubstantially longitudinal struts and a plurality of connector elementssaid connector elements connecting adjacent longitudinal struts and/orconnecting adjacent rings, the longitudinal struts comprising an axisand a cross section the cross section being normal to the longitudinalaxis of the struts, the connector elements comprising an axis and across section, the cross-section of the connector elements being normalto the axis of the connector elements, wherein the cross section of atleast some of the struts comprises a substantially triangular crosssection and the cross-section of at least some of the connector elementscomprises a substantially trapezoidal cross section.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The connector elements comprise at least two connection points        where the longitudinal struts and the connector elements are        connected.    -   The connector elements comprise three connection points and the        axis of the connector comprises a Y shaped axis or a T shaped        axis.    -   The axis of the connector elements comprises a curved axis.    -   The axis of the struts comprises a curved axis    -   The struts and connector elements are integral.    -   The struts and connector elements comprise a monolithic        structure.    -   The expandable body comprises a monolithic structure.    -   The triangular cross section of the struts comprises three        corners and the three corners comprise three filleted corners        and the filleted corners comprise a fillet radius and the fillet        radius is greater than 5 micrometers.    -   The cross section of at least some of the connector elements        comprises four corners and the four corners comprise four        filleted corners and the filleted corners comprise a fillet        radius and the fillet radius is greater than 5 micrometers.    -   The axis of the struts and connectors comprises the neutral        axis.    -   The plurality of struts and connector elements defines a porous        tube.

In another embodiment of the invention the treatment apparatus comprisesa removable device for use in the treatment of a patient with anoccluded blood vessel, said occlusion resulting from an occlusive clotlodged in the blood vessel, the device comprising an elongate member anda clot engaging structure, the elongate member configured to advance orretract the clot engaging structure in a blood vessel, the clot engagingstructure comprising an expanded state and a collapsed state and anouter tubular sub-structure and an inner tubular substructure, the outertubular substructure comprising an expandable substructure and the innertubular structure comprising an expandable substructure, the outertubular substructure comprising an inner lumen and the inner tubularsubstructure being substantially within the lumen of the outer tubularsubstructure, the inner tubular substructure comprising a high radialforce relative to the outer tubular substructure the outer tubularsubstructure substantially isolating the inner tubular substructure fromdirect contact with the vessel wall in the expanded state.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The elongate member comprises a distal end and a proximal end        and the device further comprises an attachment region.    -   The attachment region comprises a coupling between the elongate        member and the outer tubular substructure.    -   The attachment region comprises a coupling between the elongate        member and the inner tubular substructure.    -   The outer substructure comprises a plurality of struts.    -   The outer substructure comprises a closed distal end.    -   The outer tubular substructure extends distal of the distal end        of the inner tubular substructure.    -   The closed distal end comprises a cap, the cap comprising a mesh        structure.    -   The closed distal end comprises plurality of struts converging        to a closed distal end.    -   The closed distal end comprises a bullnose shape, the bullnose        comprising a longitudinally compressible structure.    -   The closed distal end comprises a filtering structure and the        filtering structure comprising a plurality of struts, the        plurality of struts substantially defining the shape of the        filtering structure.    -   The outer tubular substructure comprises at least one region of        articulation such that in a curved vessel segment the outer        tubular structure can articulate.

In another embodiment of the invention the treatment apparatus comprisesa removable device for use in the treatment of a patient with anoccluded blood vessel, said occlusion resulting from an occlusive clotlodged in the blood vessel, the device comprising an elongate member andat least one expandable structure, the elongate member configured toadvance or retract the at least one expandable structure in a bloodvessel, the at least one expandable structure comprising an expandedstate and a collapsed state and further comprises a plurality of strutsand a plurality of connectors said plurality of struts connected by saidplurality of connectors, the plurality of struts and connectorsconfigured to form tubular structure, the tubular structure comprisingan inner surface and an outer surface in both the expanded and collapsedstates, each strut comprising a corresponding inner surface and acorresponding outer surface, at least one eyelet extending through atleast one strut, the at least one eyelet comprising an axis, wherein theaxis of the at least one eyelet extends in a straight line through thestrut and the axis of the at least one eyelet is spaced apart from theouter surface of the strut and is also spaced apart from the innersurface of the strut, the at least one expandable structure comprising amonolithic structure.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The axis of the eyelet is oriented in a substantially        circumferential direction.    -   The axis of the eyelet is oriented parallel to a tangent to the        outer surface of the strut.    -   The axis of the eyelet is oriented parallel to a tangent to the        inner surface of the strut.    -   The axis of the eyelet intersects the outer surface of the        tubular member and the point of intersection of the axis of the        eyelet and the outer surface of the tube is spaced apart from        the strut.    -   The axis of the eyelet intersects the inner surface of the        tubular member and the point of intersection of the axis of the        eyelet and the inner surface of the tube is spaced apart from        the strut.    -   The at least one strut comprises a first cut surface, the first        cut surface defining the thickness of the tube and extending        substantially radially between the outer surface of the strut        and the inner surface of the strut, the at least one eyelet        penetrating the first cut surface.    -   The strut comprises a second cut surface and the eyelet extends        between the first cut surface and the second cut surface.    -   The device further comprises a fibre, the fibre penetrating        through the at least one strut through the eyelet.    -   The at least one eyelet comprises a plurality of eyelets        arranged around at least one circumference of the expandable        structure, the device further comprises at least one fibre, the        at least one fibre extending around the least one circumference        of the device, the diameter of the fibre being at least as small        as the diameter of the plurality of eyelets and the fibre        extending through a number of the plurality of eyelet.    -   The at least one circumference comprises a plurality of        circumferences and said plurality of circumferences are arranged        such that the at least one fibre and the expandable structure        comprise a porous mesh.    -   The porous mesh comprises a distal porous mesh, and the pore        size of the porous mesh is sized to capture fragments that may        be liberated during the treatment of the patient.    -   The porous mesh comprises a scaffolding structure over at least        a portion of the surface of the expandable structure.

In still another aspect of the invention the treatment apparatuscomprises a device for removing an occlusive clot from a blood vessel,the device comprising an elongate member and a clot engaging structure,the elongate member configured to advance or retract the clot engagingstructure in a blood vessel, the clot engaging structure comprising anexpanded state and a collapsed state and a plurality of strut members,the clot engaging substructure further comprising an outer tubularsub-structure and an inner tubular substructure, the outer tubularsubstructure comprising an elongate body with an inner lumen and theinner tubular substructure being substantially within the lumen of theouter tubular substructure, the elongate body of the outer tubularsub-structure comprising a body portion and a distal portion, said bodyportion and distal portion comprising a plurality of struts, and each ofsaid struts having a cross sectional area, wherein the averagecross-sectional area of struts at a cross-section in the distal portionis less than the average cross-sectional area of struts at a crosssection in the proximal portion.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The proximal portion of the outer tubular substructure may        comprise a first ring and a second ring and each of said first        and second rings may comprise a distal end, a mid-portion and a        proximal end.    -   The average cross-sectional area of struts in the mid portion of        the first ring may be substantially the same as the average        cross-sectional area of struts in the mid portion of the second        ring.    -   The distal portion of the outer tubular substructure may        comprise at least one strut and each strut may comprise a distal        end, a mid-portion and a proximal end.    -   The cross sectional area in the mid portion of the at least one        strut may change along the length of the mid portion of the at        least one strut.    -   The cross sectional area of the at least one strut may decrease        towards the distal end of the mid portion of the strut.    -   The distal and proximal ends of the at least one strut may        comprise a connector element wherein the connector element        comprises a crown, a collar or a junction.    -   The distal and proximal end of the first ring and second ring        may comprise a connector element wherein the connector element        comprises a crown, a collar or a junction.    -   The distal end of the outer tubular structure may comprise a        closed distal end.    -   The closed distal end may comprise a plurality of struts        converging to a distal junction.    -   The closed distal end may comprise a plurality of tapering        struts converging to a distal junction.    -   The inner tubular substructure may comprise a plurality of        struts.

In still another aspect of the invention the treatment apparatuscomprises a removable device for use in the treatment of a patient withan occluded blood vessel, said occlusion resulting from an occlusiveclot lodged in the blood vessel, the device comprising an elongatemember and a clot engaging structure, the elongate member configured toadvance or retract the clot engaging structure in a blood vessel, theclot engaging structure comprising an expanded state and a collapsedstate, the expandable body configured to provide a radial force as itexpands from its collapsed state to its expanded state, the devicecomprising a first substructure and a second substructure, the firstsubstructure providing a first radial force and the second substructureproviding a second radial force, the first and second substructuresconfigured such that the radial force of the first substructure and theradial force of second substructure act in unison as the expandable bodyexpands from the collapsed state to the expanded state.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The first substructure comprises a first expanded diameter and        the second substructure comprises a second expanded diameter and        the first expanded diameter is greater than the second expanded        diameter.    -   The radial force of the first substructure and the radial force        of second substructure act in unison as the expandable body        expands from the collapsed state to the second expanded        diameter.    -   The expansion of the second substructure stops at the second        expanded diameter.    -   The expansion of the first substructure stops at the first        expanded diameter.    -   The first substructure acts alone between the second expanded        diameter and the first expanded diameter.    -   The first substructure comprises a plurality of struts arranged        into a monolithic structure.    -   The second substructure comprises a plurality of struts arranged        into a monolithic structure.    -   The expansion of the expandable body from the collapsed state to        the expanded state comprises a plurality of transition states.    -   The plurality of transition states comprises a plurality of        transition diameters    -   The radial force of the expandable body decreases as the        transition diameter increases.    -   The collapsed state is defined by the inner lumen of restraining        catheter.    -   The expanded state comprises the relaxed state of the expandable        body.    -   The expandable body is biased towards the expanded state.    -   The first substructure comprises at least one proximal strut        connecting the proximal portion of the first substructure to the        elongate member.    -   The second substructure comprises at least one proximal strut        said at least one proximal strut connecting the proximal portion        of the second substructure to the elongate member.    -   The second substructure is at least partially internal to the        first substructure.    -   The second substructure is enclosed by the first substructure.

A process for the manufacture of an expandable device for use in thetreatment of a blood vessel the device comprising an expandablestructure is disclosed, the expandable structure comprising a collapseddelivery configuration for advancement through a catheter to a treatmentblood vessel and an expanded configuration wherein the expandedstructure assumes an expanded state when the device is released from thelumen of the catheter, the device comprising a structure manufacturedfrom an elongate tube, the tube comprising an outer circumferentialboundary and inner lumen, the manufacturing process comprising a cuttingprocess with a cut trajectory for cutting a pattern of struts from theelongate tube, wherein the process comprises, a first cut trajectorypassing through the circumferential boundary and entering the tube wallcutting a pattern of struts creating at least one first cut space and atleast one first cut surface, a second cut trajectory passing through thecircumferential boundary at the first cut space entering the tube wallthrough the first cut surface.

Enhancements or variants of the above process may include a processwherein the process comprises the first cut trajectory exiting the tubewall at the inner lumen; wherein the process comprises the second cuttrajectory exiting the tube wall in a first cut space; wherein theprocess comprises the second cut trajectory exiting the tube wall at theinner lumen; wherein the process comprises a laser cutting process;wherein the process comprises changing cut trajectory by displacing thetube; wherein the process comprises changing cut trajectory by rotatingor translating the tube; wherein the process comprises changing cuttrajectory by rotating or translating the tube relative to the axis ofthe tube; wherein the process comprises the first cut space being voidof material.

Another disclosed process is for the manufacture of an expandable devicefrom a tube for use in a blood vessel, the device comprising anexpandable structure, the expandable structure comprising a collapseddelivery configuration for advancement to a target site within a bloodvessel and an expanded configuration wherein the expandable structureassumes an expanded state, wherein the manufacturing processcomprises:—a first step in which a cutting tool creates at least one cutthrough the wall of the tube passing from the outside surface to theinside surface and resulting in a first cut surface, and a second stepin which the cutting tool creates at least one additional cut through aportion of the tube without removing material from the outside surfaceof the tube.

Enhancements or variants of the above process may include a process inwhich the expandable device is a self expanding device; in which thefirst cut surface defines the side walls of struts of a monolithicexpandable device; in which the second step creates at least one cutthrough the first cut surface; in which the at least one cut through thefirst cut surface creates an eyelet through a strut; in which the atleast one cut through the first cut surface removes material from theinner lumen of the tube to reduce the strut wall thickness.

Yet another disclosed process of this invention is for the manufactureof an expandable device from a tube for use in a blood vessel, thedevice comprising an expandable structure, the expandable structurecomprising a collapsed delivery configuration for advancement to atarget site within a blood vessel and an expanded configuration whereinthe expandable structure assumes an expanded state, wherein themanufacturing process involves the use of a tool to selectively removematerial from the tube, said manufacturing process comprising a firststep in which the tool enters the outer surface of the tube and exitsthe inner surface of the tube creating at least one first cut surface,and a second step in which the tool enters the first cut surface withoutcontacting the outer surface of the tube.

Such a process may involve the tool entering and exiting the first cutsurface without contacting the outer surface of the tube. The toolitself may be a laser beam, a high frequency material ablating laserbeam, a water jet or a cutting tool. The tube material may be asuperelastic or pseudoelastic material, nitinol, stainless steel, MP35Nor a steel alloy.

Yet another disclosed process of this invention is for the manufactureof an expandable device for use in the treatment of a blood vessel thedevice comprising an expandable structure, the expandable structurecomprising a collapsed delivery configuration for advancement through acatheter to a treatment blood vessel and an expanded configurationwherein the expandable structure assumes an expanded state, the devicetranslating between the collapsed state and the expanded state when thedevice is released from the lumen of the catheter, the device furthercomprising a structure manufactured from an elongate tube, wherein theprocess comprises cutting a slot pattern in the elongate tube such thatthe slots of the slot pattern extend through the wall thickness of thetube, the pattern comprising at least one strut wherein the at least onestrut comprises a first cut surface and a second cut surface, thecutting step further comprising the removal of material adjacent thefirst cut surface and the second cut surface of at least one strut andcutting a secondary pattern through the strut the secondary patternextending from the first cut surface through the wall of the strut. Thisprocess may also comprise displacing the elongate tube through adisplacement angle in advance of cutting the secondary pattern, and mayalso comprise passing the cutting laser beam through the space left bythe removal of material adjacent to the first cut or the second cut.

In still another aspect of the invention the treatment apparatuscomprises a clot retrieval device for removing occlusive clot from ablood vessel, the device comprising an inner elongate body having acollapsed delivery configuration and an expanded deployed configuration;an outer elongate body at least partially overlying the inner elongatebody; the outer elongate body being expandable relative to the innerelongate body to a radial extent which is greater than the radial extentof the inner body in the deployed configuration.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The device comprises an elongate member having a proximal end        and a distal end, the inner elongate body being connected to the        elongate member adjacent to the distal end thereof, the inner        elongate body being expandable relative to the elongate member.    -   The outer elongate body is connected to the elongate member        adjacent to the distal end thereof, the outer elongate body        being expandable relative to the elongate member.    -   The proximal end of the elongate member is adapted to extend        exterior of the patient.    -   In the expanded configuration, the outer elongate body is        radially spaced-apart from the inner elongate body to define        therebetween an interior reception space and wherein the outer        elongate body has at least one opening to receive clot.    -   The outer elongate body has an outer clot engaging region which        is adapted, on engagement with clot, to urge clot towards the        opening and into the interior reception space.    -   The outer elongate body comprises a plurality of clot-receiving        openings.    -   The outer elongate body comprises a plurality of clot engaging        regions.    -   The inner elongate body is generally tubular.    -   The inner elongate body comprises a non-circular cross-section.    -   The outer surface of the inner elongate body has a greater        surface roughness than the outer surface of the outer elongate        body.    -   The outer elongate body is generally tubular.    -   The outer elongate body comprises at least two segments which        are longitudinally spaced-apart.    -   Two of said segments are connected by members comprising hinge        elements.    -   At least one segment is movable relative to another segment.    -   The device comprises linkages between the segments.    -   The linkages are adapted for controlled movement between the        segments.    -   The device comprises a distal capture net for trapping clot        material.    -   The capture net is connected to the outer elongate body or the        inner elongate body.    -   The capture net is mounted to or provided by a distal segment of        either the outer elongate body and/or the inner elongate body.    -   The capture net is mounted to a distal portion of the elongate        member.    -   The capture net comprises a plurality of radially inwardly        projecting strut elements.    -   The capture net comprises one or more fibers.    -   The device comprises a plurality of fibre attachment eyelets to        which said fibers are attached.    -   The elongate member comprises an assembly of at least one        elongate wire and at least one elongate tubular member.    -   Said elongate tubular member comprises a coil.    -   The elongate wire is slidably movable relative to the elongate        tubular member.    -   Movement of the elongate wire relative to the elongate tubular        member effects movement of the outer elongate body relative to        the inner elongate body and/or a distal capture net.    -   The outer elongate body comprises a plurality of struts, each        strut having a vessel contacting surface, an inner surface, a        proximally facing surface and a distally facing surface, said        proximally facing surface comprising at least one protrusion.    -   The inner elongate body comprises a braided structure.    -   The inner and/or outer elongate bodies are slidably attached to        a distal region of the elongate member, such that movement of        the elongate member can be effected without resultant movement        of the inner and/or outer elongate bodies.    -   The distal ends of the inner and outer elongate bodies are        connected to one another.    -   The distal ends of the inner and outer elongate bodies are        connected to one another by a compliant element.    -   The compliant element comprises a spring.

In still another aspect of the invention the treatment apparatuscomprises a clot retrieval device for removing occlusive clot from ablood vessel of a patient, the device comprising an elongate body whichis expandable within a clot; the elongate body having outer clotengaging regions and openings into an interior space defined by theelongate body; the clot engaging regions being adapted, on engagementwith clot to urge the clot towards the openings and into the interiorreception space.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The device further comprises an elongate member having a        proximal end and a distal end the distal end of said elongate        member being connected to the elongate body, and the proximal        end of said elongate member extending exterior of the patient.    -   The elongate body is an outer elongate body and the device also        comprises an inner elongate body which is at least partially        overlayed by the outer elongate body, the outer elongate body        being expandable relative to the inner elongate body to a radial        extent which is greater than the radial extent of the inner body        in the deployed configuration.    -   The inner elongate body comprises a generally tubular structure        of interconnected struts.    -   The outer elongate body comprises two or more segments, at least        some of the segments being connected to an adjacent segment by        at least one flexible connecting element.    -   The device comprises a distal capture net.    -   The capture net comprises a plurality of radially inwardly        projecting strut elements.    -   The capture net comprises one or more fibers.    -   The device comprises a plurality of fibre attachment eyelets to        which said fibers are attached.

In still another aspect of the invention the treatment apparatuscomprises a clot retrieval device for use in the treatment of a patientwith an occluded blood vessel, the device comprising an elongate shaftand a clot engaging structure, the clot engaging structure beingconnected to the distal end of the elongate shaft and the proximal endof the elongate shaft extending exterior of the patient, the clotengaging structure comprising an outer wall and an inner receptionspace, said outer wall comprising a plurality of scaffolding sectionsand a plurality of inlet sections, said sections configured to urge clotinto the inner reception space.

In certain embodiments of the above device and of other devices of thisinvention:

-   -   The elongate body is an outer elongate body and the device also        comprises an inner elongate body which is at least partially        overlayed by the outer elongate body, the outer elongate body        being expandable relative to the inner elongate body to a radial        extent which is greater than the radial extent of the inner body        in the deployed configuration.    -   The inner elongate body comprises a generally tubular structure        of interconnected struts.    -   The outer elongate body comprises two or more segments, each        segment connected to the adjacent segment by two or one flexible        connecting elements.    -   The device comprises a distal capture net.    -   The capture net comprises a plurality of radially inwardly        projecting strut elements.    -   The capture net comprises one or more fibers.    -   The device comprises a plurality of fibre attachment eyelets to        which said fibers are attached.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is an isometric view of a clot retrieval device of thisinvention.

FIG. 1 b is a section through the shaft of the device of FIG. 1 a.

FIGS. 2 a-f show a method of use of the device of FIG. 1 a.

FIG. 3 a shows another clot retrieval device of this invention.

FIG. 3 b shows a developed view of the engaging basket of FIG. 3 a,

FIG. 4 shows another clot retrieval device of this invention.

FIG. 5 shows another clot retrieval device of this invention.

FIG. 6 shows an expandable basket portion of the clot retrieval deviceof this invention.

FIG. 7 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 8 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 9 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 10 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 11 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 12 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 13 a shows an expandable basket portion of another clot retrievaldevice.

FIG. 13 b shows a developed view of the device of FIG. 13 a.

FIG. 13 c shows the device of FIG. 13 a deployed in a clot.

FIG. 13 d shows the device of FIG. 13 a deployed in a curved vessel.

FIG. 14 a shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 14 b shows a developed view of the device of FIG. 14 a.

FIG. 14 c shows the device of FIG. 14 a deployed in a clot.

FIG. 14 d shows the device of FIG. 14 a deployed in a curved vessel.

FIG. 15 a shows a developed view of another expandable basket.

FIG. 15 b shows an isometric view of the device of FIG. 15 a.

FIG. 16 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 17 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 18 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 19 shows an expandable basket portion of another clot retrievaldevice of this invention.

FIG. 20 a shows the proximal end of an expandable basket of thisinvention.

FIG. 20 b shows the proximal end of another expandable basket of thisinvention.

FIG. 21 a shows another clot retrieval device of this invention.

FIG. 21 b is an end view of the device of FIG. 21 a deployed in a clot.

FIG. 22 a shows the distal end of an expandable basket of thisinvention.

FIGS. 22 b-e show various clot gripping features of this invention.

FIG. 23 a shows a section of an expandable basket frame cut from a tube.

FIG. 23 b shows an isometric view of a section of an expandable basket.

FIG. 23 c shows a section through a strut of FIG. 23 b in a vessel.

FIGS. 23 d-f show sections through a strut of fig the device in FIG. 23b.

FIG. 24 a shows a portion of another clot retrieval device of thisinvention.

FIG. 24 b shows a detail view of the distal end of the device in FIG. 24a.

FIG. 24 c shows the device of FIG. 24 b compressed as for delivery.

FIGS. 25 a-d show various fibre attachment features.

FIG. 26 a shows another clot retrieval device of this invention.

FIG. 26 a shows yet another clot retrieval device of this invention.

FIG. 27 shows another clot retrieval device of this invention.

FIG. 28 shows another clot retrieval device of this invention with adetachable net.

FIG. 29 shows a close-up view of the end of the device of FIG. 28.

FIG. 30 shows yet another clot retrieval device of this invention.

FIGS. 31 a-e show various capture nets of this invention.

FIGS. 32 a-c show another clot retrieval device of this invention beingdeployed.

FIG. 33 shows yet another clot retrieval device of this invention.

FIG. 34 shows yet another clot retrieval device of this invention.

FIG. 35 a-e show an actuatable clot retrieval device of this invention.

FIG. 36 shows another actuatable clot retrieval device of thisinvention.

FIG. 37 shows another actuatable clot retrieval device of thisinvention.

FIG. 38 shows another clot retrieval device of this invention.

FIG. 39 a-e show another actuatable clot retrieval device of thisinvention.

FIG. 40 shows another actuatable clot retrieval device of thisinvention.

FIG. 41 shows another actuatable clot retrieval device of thisinvention.

FIG. 42 shows another actuatable clot retrieval device of thisinvention.

FIG. 43 a-f show various radiopaque features and coatings.

FIGS. 44 a-h show a method of use of a device of this invention.

FIG. 45 shows a graph of the results of testing on clot properties.

FIG. 46 shows another clot retrieval device of this invention.

FIG. 47 shows a developed view of another expandable basket of thisinvention.

FIG. 48 a shows another clot retrieval device of this invention deployedin a clot.

FIG. 48 b-d show views of a ring of the device from FIG. 48 a.

FIG. 49 shows a ring of an expandable basket of this invention.

FIG. 50 shows yet another clot retrieval device of this invention.

FIG. 51 a shows another clot retrieval device of this invention.

FIG. 51 b shows a detailed view of a section through the distal end ofFIG. 51 a.

FIG. 52 a shows another clot retrieval device of this invention.

FIG. 52 b shows the distal end of a clot retrieval device of thisinvention.

FIG. 52 c shows a close-up of a proximal collar of a clot retrievaldevice of this invention.

FIG. 53 a shows an inner tubular member of this invention.

FIG. 53 b shows another inner tubular member of this invention.

FIGS. 53 c-h show sections through tubular members of this invention.

FIG. 54 shows a developed view of a device of this invention.

FIG. 55 shows a sectioned side view through a device of this invention.

FIG. 56 a shows an inner tubular member in a bend.

FIG. 56 b shows a section through the device of FIG. 56 a.

FIG. 57 a shows an inner tubular member in a bend.

FIG. 57 b shows a section through the device of FIG. 57 a.

FIG. 58 a shows an outer member of a stent-basket.

FIG. 58 b shows a developed view of the device of FIG. 58 a.

FIG. 59 a shows another outer member of a stent-basket.

FIG. 58 b shows a developed view of the device of FIG. 59 a.

FIG. 60 a shows a developed view of an outer member.

FIG. 60 b shows a close-up of an atraumatic crown feature.

FIG. 60 c shows a close-up of another atraumatic crown feature.

FIG. 61 shows another clot retrieval device of this invention.

FIG. 62 shows another outer tubular member of this invention.

FIG. 63 a shows another outer tubular member of this invention.

FIG. 63 b shows the device of FIG. 63 a in a bend.

FIG. 64 a shows another outer tubular member of this invention.

FIG. 64 b shows yet another outer tubular member of this invention.

FIG. 65 a shows an engaging basket of this invention.

FIG. 65 b shows a top view of a portion of an engaging basket.

FIG. 66 shows the distal end of an engaging basket of this invention.

FIG. 67 shows the distal end of an outer member of this invention.

FIG. 68 shows a close-up of a strut structure of an engaging basket.

FIG. 69 shows a section through a tube from which the structure of FIG.68 could be machined.

FIG. 70 a shows the distal end of an engaging basket of this invention.

FIG. 70 b shows an end view of the device of FIG. 70 a.

FIG. 71 shows the distal end of an engaging basket of this invention.

FIG. 72 shows the distal end of an engaging basket of this invention.

FIG. 73 shows the distal end of an engaging basket of this invention.

FIG. 74 a shows a side view of an engaging basket of this invention.

FIG. 74 b shows the device of FIG. 74 a in a wrapped configuration.

FIG. 75 shows a graph of radial force against device diameter.

FIGS. 76 a-c show a clot retrieval device retrieving clot from a vessel.

FIGS. 77 a-b show a clot retrieval device retrieving a clot.

FIGS. 78 a-b show a clot retrieval device retrieving a clot.

FIGS. 79 a-d show a clot retrieval device retrieving a clot from avessel.

FIG. 80 shows a distal tip of a clot retrieval device.

FIG. 81 shows a distal tip of a clot retrieval device.

FIG. 82 shows a distal tip of a clot retrieval device.

FIGS. 83 a-b show a stent-basket interacting with a clot in a vessel.

FIG. 84 shows a cross section through an elongate tube.

FIG. 85 a shows an isometric view of a device being machined from atube.

FIG. 85 b shows an end view of a device being machined from a tube.

FIG. 86 shows a sectional end view of a device machined from a tube.

FIG. 87 is an isometric view of a portion of a clot retrieval device.

FIG. 88 shows a sectional end view of a device being machined from atube.

FIG. 89 a is an isometric view of struts with side holes.

FIG. 89 b shows a sectional end view of the device of FIG. 89 a in adelivery configuration.

FIG. 90 a is an isometric view of struts with eyelets and fibres.

FIG. 90 b is a sectional view through a strut and fibre of FIG. 90 a.

FIG. 91 a is an isometric view of struts with eyelets and fibres.

FIG. 91 b is a side view of a strut and fibre of FIG. 91 a.

FIG. 91 c is an isometric view of struts with eyelets and fibres.

FIG. 92 a shows a sectional end view of a strut being machined from atube.

FIG. 92 b is an isometric view of profiled struts.

FIG. 93 a shows a sectional end view of a strut being machined from atube.

FIG. 93 b is an isometric view of profiled struts.

FIG. 94 is an isometric view of profiled struts.

FIG. 95 shows a sectional end view of a device in a deliveryconfiguration.

FIG. 96 shows a sectional end view of a device in a deliveryconfiguration.

FIG. 97 is an isometric view of a portion of a clot retrieval device.

FIG. 98 a is a developed view of the body of an outer member of a clotretrieval device.

FIG. 98 b is a developed view of a portion of an outer member of a clotretrieval device.

FIG. 99 a is a side view of a clot retrieval device.

FIG. 99 b is a side view of the inner tubular member of the device ofFIG. 99 a.

FIG. 99 c is a side view of the outer member of the device of FIG. 99 a.

FIG. 99 d is a developed view of the body of the outer member of thedevice of FIG. 99 a.

FIG. 99 e is an isometric view of the proximal end of the stent-basketof FIG. 99 a.

FIG. 99 f is an isometric view of the distal end of the stent-basket ofFIG. 99 a.

FIG. 100 is a side view of another clot retrieval device.

FIG. 101 is a developed view of an outer member of a clot retrievaldevice.

FIG. 102 is a side view of a portion of another clot retrieval device.

FIG. 103 is a detail view of a portion of another clot retrieval device.

FIG. 104 is a side view of a portion of another clot retrieval device.

FIG. 105 a is a side view of another clot retrieval device.

FIG. 105 b is a side view of another clot retrieval device.

FIG. 105 c is a side view of another clot retrieval device.

FIG. 106 a is a side view of a distal portion of another clot retrievaldevice.

FIG. 106 b is an end view of the device of FIG. 106 a.

FIG. 107 is an isometric view of the distal portion of a clot retrievaldevice.

FIG. 108 is a graph of blood flow rate against clot type.

DETAILED DESCRIPTION

Specific embodiments of the present invention are now described indetail with reference to the figures, wherein identical referencenumbers indicate identical or functionality similar elements. The terms“distal” or “proximal” are used in the following description withrespect to a position or direction relative to the treating physician.“Distal” or “distally” are a position distant from or in a directionaway from the physician. “Proximal” or “proximally” or “proximate” are aposition near or in a direction toward the physician.

Accessing cerebral, coronary and pulmonary vessels involves the use of anumber of commercially available products and conventional proceduralsteps. Access products such as guidewires, guide catheters, angiographiccatheters and microcatheters are described elsewhere and are regularlyused in cath lab procedures. It is assumed in the descriptions belowthat these products and methods are employed in conjunction with thedevice and methods of this invention and do not need to be described indetail.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description of the invention is in the contextof treatment of intracranial arteries, the invention may also be used inother body passageways as previously described.

Referring now to FIG. 1 a, there is shown one of the preferredembodiments of the clot retrieval device 1 of the present invention. Theclot retrieval device 1 has an elongate shaft 9 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, a clot engaging portion configured at the distal end ofthe elongate shaft 9 having an engaging basket 2, an inner tubularmember 5 to facilitate restoration of blood flow through clotimmediately after the clot retrieval device 1 is deployed at anobstructive site, and an outer member 8 comprising scaffolding sections16 and a plurality of inlet mouths 4 and defining a reception space 15,and a distal capture net 3 attached to a distal capture net shaft 10 byconnection strut 17 at a distal end while the proximal end extendsexterior of the artery. The distal capture net 3 has a net 7 mounted ona frame 6. In one embodiment the distal capture net 3 and clot engagingportion 2 are made of a shape-memory material, preferably nitinol, andare self-expandable from a collapsed configuration to an expandedconfiguration. The distal capture net shaft 10 runs through the elongateshaft 9 to enable the physician to manually control and move the distalcapture net 3 and engaging basket 2 independently using a handle 11,which may be detachable from these shafts. The proximal capture netshaft 14 has a connection zone 13 to which a shaft extension 12 may beconnected to facilitate the movement and exchange of the engaging basketand/or microcatheters or other devices. In another embodiment shafts 14and 12 are connected at connection zone 13 by a detachable connectionwhich may be separated to shorten the capture net shaft if deviceexchanges are not desired.

The elongate basket 2 comprises a collapsed configuration for deliveryand an expanded configuration for clot engagement and retrieval. Theouter member 8 of the elongate basket 2 may be shaped in a variety ofways as shown in other figures in this document, and may have a varietyof clot gripping features, some of which are shown in FIGS. 22 a-d, andmay be articulated to enable it to retain its expanded shape intortuosity, and may be configured so that the user can control itsexpansion.

Expansion of the elongate basket 2 causes compression and/ordisplacement of the clot 22 during expansion. When an expandable bodyprovides excellent scaffolding the clot 22 is compressed. When anexpandable body provides an escape path or opening the expanding bodywill urge the clot 22 towards the opening. However if the expandablebody provides only modest scaffolding the clot will be displaced butsince the clot has many degrees of freedom it may move in a variety ofdifferent directions and therefore cannot be controlled. By providing atubular expandable body where the length of the tubular expandable bodyis substantially as long as the length of the occlusive clot 22 orlonger, many of the degrees of movement freedom available to the clot 22are removed. When, as with the current invention, inlet openings 4 areprovided in the expandable body 8 these inlets 4 provide the primarymovement freedom available to the clot 22 and so the expansion of theexpandable body 8 urges the clot 22 into the reception space 15. Theelongate basket 2 has multiple inlet mouths 4 to accept the clot 22. Inthis way inlet mouths 4 allow portions of the clot 22 to enter receptionspace 15 of the elongate basket 2, and thus allow the clot 22 to beretrieved without being excessively compressed. This is advantageousbecause the inventors have discovered that compression of clot causes itto dehydrate, which in turn increases the frictional properties of theclot, and increases its stiffness, all of which makes the clot moredifficult to disengage and remove from the vessel. This compression canbe avoided if the clot migrates inward through the wall of the basket 2as the baskets porous structure migrate outward towards the vessel wall.

The inlet mouths 4 provide the added benefit of allowing the basket 2when retracted to apply a force to the clot in a direction substantiallyparallel to the direction in which the clot is to be pulled from thevessel (i.e. substantially parallel to the central axis of the vessel).This means that the outward radial force applied to the vasculature maybe kept to a minimum, which in turn means that the action of the clotretrieval device 1 on the clot 22 does not serve to increase the forcerequired to dislodge the clot 22 from the vessel, thus protectingdelicate cerebral vessels from harmful radial and tensile forces.

The inner tubular member 5 comprises a collapsed configuration fordelivery and an expanded configuration for flow restoration andfragmentation protection. In one embodiment the inner tubular member 5is a tubular braided structure which is connected to the shaft 9 at itsproximal end and is connected to the outer member 8 of the elongatebasket 2 at its distal end. In other embodiments it may comprise aknitted structure, a permeable membrane, a porous metal wall or a lasercut tube, and may be incorporated into the elongate basket in a varietyof ways as shown in subsequent figures. The inner tube 5 may comprise anelastic or super-elastic of shape-memory metallic structure and mayfurther comprise a polished surface such as an electropolished surface.The inner tubular member 5 is configured so as to provide a flow lumenthrough the device 1 to facilitate the immediate restoration of bloodflow past the clot 22 upon deployment. In one embodiment the inner tube5 is configured to scaffold said flow lumen through the clot 22 toprevent the liberation of fragments which might otherwise lodge in thedistal vasculature and the inner tube 5 may grip the clot to assist inits removal. In other embodiments the inner tube 5 may be configured tobe actuated by the user so that the user can apply an expansion forcewhich assists to open a flow lumen. This expansion force may also serveto firmly engage the elongate basket 2 in the clot 22.

The frame 6 of the capture net 3 may be a self expanding nitinol member,comprising a number of connected strut elements. The net 7 may be of abraided, knitted or other fibrous construction and comprise one or moremonofilament or multifilament fibres, which may be made from a range ofpreferably high strength materials. Suitable polymer materials includePEN, PET, UHMWPE, LCP and Aramid, Suitable metallic materials includeNitinol, SS, MP35N and Tungsten. An advantage of using nitinol fibres isthat the formed net may be heat set to remember an expanded shape—withthe benefit that the frame 6 may be made extremely low profile and lowradial force, as it will require minimal radial force to unwrap the net7 and expand its mouth upon deployment. These fibres may be attached tothe strut elements at defined junctions, which may comprise holes,eyelets, undulations, recesses or protrusions, similar to thoseillustrated for the elongate basket is FIGS. 24 and 25.

In this and other embodiments the capture net may take a variety ofshapes many of which are shown in FIGS. 31 a-e. It may be attached to anindependent shaft as shown, it may be directly attached to the outermember 8 or the inner tubular member 5 of the elongate basket 2, or tothe distal section of the device shaft 9. It may be attached to theelongate basket 2 or distal shaft slideably or by a flexible tether. Itmay even be integral to the elongate basket 2 such as is shown in FIG.27, or may be integral but detachable as shown in FIG. 28.

FIG. 1 b shows a cross section through one embodiment of the distalshaft 9 of the device 1 shown in FIG. 1 a. Outer shaft 18 is a tubularmember with an inner liner 19, through which runs the capture net shaft10. Outer shaft 18 may be a slotted metallic tube, or a wound wire tubeor a polymer tube, or a polymer tube with braided reinforcement, or anassembly of any of these. Inner liner 19 may comprise a low frictionmaterial such as PTFE, PE or FEP, and may be a composite of more thanone material to facilitate insertion of a low strength, low frictionmaterial into a long narrow lumen. In a preferred embodiment outer shaft18 is a hypotube with a helical laser machined distal slotted section,and liner 19 is a polyimide tube with a PTFE inner lumen, and capturenet shaft 10 is a nitinol wire with a PTFE outer layer to facilitate itsmovement through the shaft assembly.

Use of an intracranial stent-basket clot retrieval device 26 of thepresent invention in removing an obstructive clot 22 from anintracranial artery 21 is depicted in FIGS. 2 a-2 f. A guidewire 23 anda microcatheter 24 are inserted in the artery and are advanced acrossthe obstructive clot 22, which is lodged at bifurcation 34, using anyconventionally known techniques. The guidewire 23 is removed from themicrocatheter 24 to allow the clot retrieval device 26 be advancedthrough the microcatheter in a collapsed configuration until the distalcapture net 27 reaches distal of the clot 22. The microcatheter 24 isretracted to deploy the clot retrieval device 26 across the clot 22 in amanner that the distal capture net 27 is positioned distal of the clot22 and clot engaging portion of the clot retrieval device 26 ispositioned across the clot 22. The scaffolding sections 35 exert agentle outward force to urge the clot 22 into inlet mouths 32, whileproviding sufficient surface area to maintain the integrity of the clotand avoid its dissection. The inner tubular member 29 preserves theblood flow lumen and immediately restores blood flow through the clotretrieval device 26 and clot 22. The elongate shaft 30 is manuallyretracted to move the engaging basket 28 and captured clot proximally,while leaving the distal capture net 27 in the original position. Beforewithdrawing the elongate basket 28 and clot 22 into the guide catheter25, the distal capture net 27 is retracted proximally to protect agreater portion of the distal vasculature from embolization during theprocedural use of the clot retrieval device 26. The distal capture net27 expands to appose the walls of the larger proximal artery and catchany fragments 33 that may be released while clot is retracted into theguide catheter 25. The clot retrieval device 26 is then finally removedthrough the guide catheter 25 along with the clot 22 and any fragments33 it has captured. An alternative but similar method of use involvesretracting elongate basket 28 and distal capture net 27 together throughthe vasculature, rather than retracting the capture net independently.

The inventors have discovered that occlusive clots are a highly mobilethree dimensional bodies in vivo and that under the influence of anapplied force the clot will change shape, deform and/or migrate (withoutsignificant volume change) in preference to dehydrating under theinfluence of the applied force. The energy required to dehydrate theclot is in many situations greater than the energy required to changethe shape of the clot. This discovery has allowed the inventors todefine a series of new strategies for capturing and removing occlusiveclots in human vessels.

It will be appreciated that an expandable tubular device with sufficientradial force (like a stent) which moves from a small diameter collapsedstate to a larger diameter expanded state while positioned across asubstantial portion or all of a clot length will cause compression anddehydration of the clot.

The current stent-basket invention however discloses a device with aporous expandable tubular element whereby the expandable tubular elementcomprises an outer wall which comprises a plurality of scaffold regionsthat are configured to scaffold clot against the vessel wall as theexpandable tubular element expands outwardly. In one embodiment thescaffold regions are spaced apart. In another embodiment the scaffoldregions are connected to form a continuous scaffold surface. Theexpandable tubular element comprises inlet openings in the wall andthese inlet openings comprise regions with substantially no scaffolding.The inlet openings may be interspersed between scaffold regions or theinlet openings may be substantially surrounded by a continuous pluralityof scaffold regions.

The scaffold regions are configured so as to provide sufficientscaffolding and radial force so as to compress a constrained clot duringexpansion from a collapsed delivery state to at least a partiallyexpanded state. The inlet openings on the other hand are configured suchthey have little or no scaffolding over the inlet area so that clotdirectly over the inlet opening and clot from the adjacent scaffoldregion can flow, deform or migrate through the inlet opening. Theability of the invention to urge clot from the scaffold region to flow,deform or migrate through the inlet opening greatly reduces the volumeof clot in the scaffold region and this has the effect of greatlyreducing the degree to which the clot is compressed.

Preferably the device is configured such that during expansion of thestent-basket the energy required to cause at least some of the clot thatis radially outward of a scaffolding region to flow, deform or migratetowards or through an adjacent inlet is less than the energy needed tocompress (and dehydrate) the clot to a significant degree.

Preferably the device is configured such that during the expansion ofthe device in an occlusive clot that at least some of the clotsandwiched between a scaffold region and the vessel wall is urgedtowards or into an adjacent inlet opening.

Preferably the stent-basket device is configured such that during theexpansion of the device in an occlusive clot that substantially all ofthe clot that is at the inlet opening will pass through the inletopening as the expandable stent-basket expands.

Preferably the relative size and area of the scaffolding regions and theinlet openings is such that the stent-basket can expand to a fullyexpanded diameter that is between 2 times and 18 times that of thecollapsed diameter of the stent-basket.

FIGS. 3 a, 3 b, 4 and 5 illustrate three general constructions of thedevice of this invention, said constructions being applicable to all ofthe more detailed descriptions provided elsewhere. FIG. 3 a depicts aclot retrieval device 51 with an elongate shaft 55 having a distal endthat extends interior of the artery and a proximal end that extendsexterior of the artery, an engaging basket 52 configured at the distalend of the elongate shaft 55 to trap and engage clot without exercisingexcessive compression force on clot, and a distal capture net 53attached to a capture net shaft 54 at a distal end while proximal endextends exterior of the artery. The distal capture shaft 54 run throughthe elongate shaft 55 to enable the physician to manually control andmove the distal capture net 53 and engaging basket 52 independently. Inother embodiments the elongate basket, the capture net and the shaft maytake any of the forms disclosed in the other figures of this document,the capture shaft 54 may be fixedly attached to elongate shaft 55 or thecapture net may be attached directly to the elongate basket.

FIG. 3 b shows a developed view of the engaging basket 52 of FIG. 3 a,comprising a proximal segment 60 which is connected at its proximal endto connector arm 65 and at its distal end to middle segment 61, saidmiddle segment being connected to a distal segment 62 at articulationpoint 64. Each segment comprises a network of struts and crowns,including terminal crowns 63 which are not directly connected to thedistal segment. It will be noted that at the distal end of each segmentthe number of terminal crowns 63 is greater than the number of connectedcrowns 66.

FIG. 4 illustrates stent-basket type clot retrieval device 71 which hasan elongate shaft 55 having a distal end that extends interior of theartery and a proximal end that extends exterior of the artery, anengaging basket 52 comprising multiple segments 74, configured at thedistal end of the elongate shaft 55 to trap and engage clot withoutexercising excessive compression force on clot, an inner tubular member73 to facilitate restoration of blood flow through clot and avoidfragmentation through the internal lumen, and a distal capture net 72attached to the inner tubular member 73. The inner tube 73 comprises aporous tubular structure and is configured to expand when notconstrained and the force of expansion is such as to create at least apartial flow lumen through the clot after deployment and in advance ofclot disengagement. The inner tube 73 may be a fabric or a tubularstructure and may be polymeric or metallic. Preferably the inner tube 73is a superelastic or shape memory tube. The pores in the tube 73 aresized to allow blood flow through the wall of the tube but to preventthe passage of fragments of clot that may be liberated during theprocedure. In one embodiment the distal end of the inner tube 73 istapered. In one embodiment the distal end of the inner tube 73 istapered outwardly and the tapered end defines a closed end to the stentbasket 52. The distal capture net 72 is configured to capture fragmentsthat may be liberated during the steps of device expansion in the clot,disengagement of the clot from the vessel segment, withdrawal of theclot through the vasculature or removal of the clot into the lumen of aremoval catheter or guide catheter. In other embodiments the engagingbasket, the inner tubular member the capture net and the shaft may takeany of the forms disclosed in the other figures of this document; thecapture net 72 may be an integral part of the inner tubular member 73and may terminate adjacent the distal end of the engaging basket 52 ormay be spaced apart from the engaging basket and attached to either theengaging basket 52 or to the shaft 55.

FIG. 5 illustrates another slightly variant embodiment of anintracranial stent-platform based clot retrieval device 75 of thepresent invention. The clot retrieval device 75 has an elongate shaft 55having a distal end that extends interior of the artery and a proximalend that extends exterior of the artery, and an engaging basket 52configured at the distal end of the elongate shaft 55 to trap and engageclot without exercising excessive compression force on clot. In otherembodiments the engaging basket and the shaft may take any of the formsdisclosed in the other figures of this document. In another embodimentthe segments 74 comprise a plurality of closed tubular segments wherebythe struts that make up the segments define a closed cylindricalstructure. In another embodiment the segments 74 comprise a plurality ofopen tubular segments whereby the struts that make up the segmentsdefine a cylindrical structure but the cylindrical structure is notclosed. In one variant the open cylindrical structure of the segmentscomprises a C shaped structure. In one variant the open cylindricalstructure comprises a longitudinal rim. In another variant thecylindrical structure of the segments 74 comprises a pair of rimsextending longitudinally. The longitudinal extension of the rims maycomprise a linear extension, or a spiral extension or the longitudinalextension may have a circumferential component. The pair of rims may bespaced apart. The pair of rims may define a gap in the cylindricalstructure of the segment 74. The pair of rims may overlap. In anotherembodiment the device may comprise a plurality of segments 74 whereinsome of the segments comprise a closed cylindrical structure and otherscomprise an open cylindrical structure.

A range of embodiments of the elongate baskets of this invention areshown in FIGS. 6 to 12 inclusive. These devices each comprise acollapsed configuration for delivery and an expanded configuration forclot engagement and retraction, and may be made from a variety ofmaterials but preferably from a metallic material and most preferablyfrom nitinol. They are generally self expanding to their fully expandeddiameter, but may in some embodiments be actuated to achieve fullexpansion, and in other embodiments may be self expanding andactuatable. These figures disclose general shapes and constructions andare intended to be applicable to all of the elongate baskets/stentbaskets/expandable bodies disclosed elsewhere in this disclosure so thatthese details need not be repeated throughout this document.

FIG. 6 shows an engaging basket 81 eccentrically connected to a shaft 84at a proximal junction 85. The engaging basket 81 comprises multiplestruts 82 configured to provide regions of clot scaffolding 87 and aplurality of inlet mouths 83. The regions of scaffolding are configuredto exert a gentle outward radial force on the clot in which the deviceis deployed, so that the clot is urged towards the unscaffolded inletmouth regions. The scaffolded regions comprise an effective surface areagreater than that of the contact surface of the struts defining thescaffolded region, and thus can effectively urge portions of the clot tomigrate through the inlet mouths into the internal reception space 86without subjecting the clot to sufficient focal pressure to dissect orfragment the clot. In this way the inherent cohesion of the clot can bemaintained which is particularly beneficial for removing clots frombifurcations or trifurcations, and for avoiding fragmentation andconsequent distal embolization. Clot engaging features 88 may be presenton some or all of struts 82. Such features may be protrusions from theproximally facing surface of a laser cut strut, or may be configured inother ways such as are described in more detail in relation to FIGS. 22and 23. These features are particularly effective when used inconjunction with the inlet mouth designs because the inlet mouths allowthe clot to project significantly into the reception space such that theproximally facing surface of a strut at the distal perimeter of an inletmouth is substantially encapsulated by clot. This allows said strut toexert a retracting force on the clot in a direction substantiallyparallel to the direction in which the clot is to be retracted, i.e. adirection substantially parallel to the central axis of the vessel.

FIG. 7 represents a clot retrieval device of the present invention whichis a variant embodiment of the clot retrieval device illustrated in FIG.6. The clot retrieval device has a shaft 84 and an engaging basket 91substantially concentrically connected to the shaft 84 at a proximaljunction 85. The engaging basket 91 has a plurality of inlet mouths 83and a reception space 86 to trap and engage clot without exercisingexcessive compression force on clot and a plurality of struts to pin andretain the clot while removing out of the artery.

FIG. 8 represents another embodiment of a clot retrieval device of thepresent invention somewhat similar to the one shown in FIG. 6. The clotretrieval device has a shaft 84 and an engaging basket 101 eccentricallyconnected to the shaft 84 at a proximal junction 85. The engaging basket101 comprises one or more wire struts 102 configured in a generallydistally tapering shape and is made of nitinol wire.

FIG. 9 represents another embodiment of the present invention which is avariant embodiment of the clot retrieval device illustrated in FIG. 8.The clot retrieval device has a shaft 84 and an engaging basket 111substantially concentrically connected to the shaft 84 at a proximaljunction 85. The engaging basket 111 comprises one or more wire struts112 configured in a generally proximally tapering shape and is made ofnitinol wire.

FIG. 10 shows another embodiment of an engaging basket of the presentinvention. The engaging basket 151 has a seam 152 running axially alongits length and a plurality of struts 153.

In FIG. 11, the engaging basket 161 has two axial seams 162 runningpartially along its length and a plurality of struts 163.

FIG. 12 illustrates another variant of engaging basket 171 that has aseam 172 running spirally around its circumference and a plurality ofstruts 173. The seams may be spaced apart (as shown) or they may overlap(not shown) in either the collapsed state or the expanded state. Partialor full seams of this nature may be applied to any of the engagingbasket designs disclosed elsewhere.

FIGS. 13 a,b,c,d depict a conventional stent-like clot retriever asdescribed in the art and illustrate the manner in which it pins andcompresses clot, and the manner in which its shape is affected when itis placed in a bend under tension.

FIG. 13 a shows an isometric view of the stent-like clot retriever 201.

FIG. 13 b shows a developed view of the stent-like clot retriever 201,illustrating how it comprises a series of cells 212 created by struts211 whose proximal and distal ends are connected to neighbouring strutsexcept at the distal end of the device, creating an array of closedcells, which may or may not contain a seam.

FIG. 13 c shows a side view of the stent-like clot retriever 201deployed across a clot 222 in a blood vessel 221, illustrating how itcompresses the clot against the vessel wall, and does not havesignificant migration of clot through the stent-like clot retrievercells. The stent-like clot retriever applies an outward radial force 225in order to grip the clot. However the clot needs to be pulled throughthe vessel in a direction at right angles to this force, so a highradial force will be needed in order to provide an adequate grip force.The tensile force applied by the user results in force 223 being appliedto the proximal end of the stent-like clot retriever, which in turnresults in a force 224 being applied to the clot, and a tensile force226 being applied to the vessel. Force 224 needs to be high enough toovercome the friction and adhesion between the clot and vessel, butforce 224 can only be increased by increasing the radial force 225 orthe applied force 223, both of which may result in potentially harmfulforces on the vessel. Radial force 225 is also likely to causecompression of the clot, which the inventors have discovered causesdehydration of the clot and increase its coefficient of friction, makingit even more difficult to remove.

FIG. 13 d shows a side view of the stent-like clot retriever 201 beingretracted through a tortuous blood vessel 231, illustrating how it losesits shape, collapsing in diameter in region 232, which makes itdifficult for it to retain its grip on any captured clot. This occursbecause the struts of the stent-like clot retriever are placed intension when it is retracted. This tension is due to friction betweenthe device and the blood vessel, and is increased if an additional loadis applied load such as that provided by a clot. In a bend the struts onthe outside of the bend are placed in higher tension than those on theinside. In order to attain the lowest possible energy state the outsidesurface of the stent moves towards the inside surface of the bend, whichreduces the tension in the struts, but also reduces the expandeddiameter of the stent-like clot retriever.

The problems described above are addressed by the engaging basket 251shown in FIG. 14 a. The engaging basket 251 comprises a plurality ofstent like segments each comprising a distally tapering proximal end254, a body section 255, a distal end 256 and a reception space 257. Theproximal stent segment 252 is connected at its proximal end to anelongate shaft 258 which extends external of the patient, and at itsdistal end to an adjacent segment.

FIG. 14 b shows a developed view of the engaging basket 251 of FIG. 14a. Each segment comprises a plurality of struts 261, junction crowns 265and terminal crowns 264, with adjacent segments connected at connectionpoints 262 and the spaces between segments defining inlet mouths 263.

FIG. 14 c shows the engaging basket 251 when deployed across the clot272 in an artery 271, the struts 261 migrate out towards the artery wallallowing clot 272 to migrate through the previously described inletmouths 263 into the reception space 257 of the engaging basket 251. Thestruts 261 exercise minimal compression force on the clot 272 whichminimizes the amount of clot dehydration induced and hence minimizes anyincrease in t the coefficient of friction of the clot. The struts 261become embedded within the clot 272 and act on the clot 272 in adirection substantially in line with the axis of the engaging basket 251when it is retracted from the artery 271. In this manner, the engagingbasket 251 does not rely on radial force 275 to retain its grip on theclot 272 and clot 272 can be removed from the artery 271 at a low force274, which means that the forces 273 required to be exerted on the clotretrieval device and the resultant forces 276 exerted on the vasculatureare also low, resulting in a more atraumatic, lower force procedure thanwould be the case with the stent-like clot retriever design described inFIG. 13.

FIG. 14 d illustrates how the engaging basket 251 can effectively retainits shape when it is placed in a tortuous artery 281 with central axis283 and radius of curvature 282, because struts 261 are not continuouslyconnected along the length of the engaging basket 251. The terminalcrowns 264 serve to break the continuity of struts 261 and prevent thestruts 261 from being placed in significant tension when retractedthrough the tortuous artery 281.

FIGS. 15 a-15 b shows an engaging basket 301 of the present inventionwhich is slightly variant embodiment of the engaging basket 251 as shownin FIGS. 14-14 d. The engaging basket 301 has a plurality of strutshaving distal ends connected to crowns except to terminal crowns 303which results in plurality of articulation points 302 and open inletmouths 304. Some or all struts may have a plurality of clot engagementfeatures 306 and the most distal facing crowns may have a distal tab305.

FIG. 16 shows slightly variant engaging basket with a reduced number ofcells around its circumference, having similar articulation points 332and open inlet mouths 333 of the engaging basket 331.

Another varying embodiment of an engaging basket 351 of the presentinvention is shown in FIG. 17. The engaging basket 351 has a pluralityof distinct segments made of a plurality of struts 355 having distalends connected to crowns except to terminal crowns 354. Each segment isattached to a basket shaft 352 at a segment proximal collar 353 andmigrates out towards the artery wall allowing clot to migrate into theengaging basket 351. The short discrete segments of this design provideexcellent flexibility both in the compressed state for delivery througha microcatheter and in the expanded state for retraction through thevasculature. The discontinuity between the segments also allows thebasket to retain its shape in bends in a similar fashion to that shownin FIG. 14 d. As with all of the engaging baskets shown, this design mayalso comprise an inner tubular member and/or capture net.

FIG. 18 shows another elongate basket 371 of this invention comprising aplurality of folded ring elements 375 connected to each other atintersection points 373 and to an elongate shaft extending external ofthe patient by connecting arms 372 at collar 376. The distal most pointof each ring 375 is not connected to an adjacent ring and hence does nottransmit any applied load or distortion to a neighbouring ring, whichcombines with the articulating action of connection points 373 to assistin maintaining an expanded shape to firmly retain a grip on capturedclot when retracted through tortuousity. In another similar embodimentthe adjacent ring elements may be connected by pairs of axial strutelements.

FIG. 19 shows yet another variant configuration of staggeredarticulating points 393 of the engaging basket 391 of the presentinvention. The engaging basket 391 has proximal arms 392 attached to aproximal collar 396, a plurality of struts connected to crowns except toterminal crowns 395 which results in plurality of staggered articulationpoints 393 and open inlet mouths 394. Each articulation point 393 is at90 degree to the next. The proximal collar 395 is mounted on a deviceshaft 397.

FIG. 20 a shows a design by which an engaging basket 414 of the presentinvention may be attached to a proximal shaft in order to permit thebasket to rotate relative to the shaft so that it may take advantage ofits articulation features and conform to the bends of the vessel withminimal loss of expanded shape. The engaging basket 414 may be any ofthe baskets described in this invention and is attached to a proximalcollar 413 mounted on a shaft 411. The shaft 411 has a proximal stop 412and a distal stop 415, in a manner that it allows engaging basket 414rotate and to self-align into a preferred orientation in a tortuousartery. FIG. 20 b shows a slightly variant configuration in whichengaging basket 424 which may be any of the baskets described in thisinvention and is attached to shaft 421 at collar 423 by a flexibleconnection element 422. Element 422 may be a monofilament ormultifilament metallic or polymer element, such as a nitinol wire or anaramid thread.

Another preferred embodiment of an engaging basket 451 of the presentinvention is illustrated in FIGS. 21 a-21 b. The engaging basket 451 hasa plurality of smaller diameter inner segments 454 having shorter struts456 to create a flow lumen 460 through the clot and facilitaterestoration of blood flow immediately after the engaging basket 451 isdeployed across the clot, and a plurality of larger diameter outersegments 453 having longer struts 455 to accommodate a broad artery sizerange and allow engaging basket 451 retaining the clot while withdrawinginto progressively larger diameter proximal arteries. The most proximalouter segment 453 is attached to a proximal collar mounted on a shaft452 and the most distal outer segment is attached to a capture net 461.Each distal crown 458 of outer segment 453 is connected to inner segment454 by connecting arms 457. The space between the outer segment 453 actsas inlet mouths 462 to trap and engage clot without exercising excessivecompression force on clot. FIG. 21 b shows an end view of the device inwhich clot 459 has migrated between outer segments 453, and isscaffolded by the struts of inner segment 454 from obstructing flowlumen 460.

FIGS. 22 a-22 e depicts clot engagement features of an engaging basket471 of the present invention. The engaging basket 471 has a plurality ofstruts 474. Each strut 474 is having a plurality of clot engagementfeatures 474. The clot engagement feature 474 can be an eyelet 475 or atab 476 or an arm 477 or combinations thereof. The most distal facingcrown 479 may have a distal clot grip feature 473. FIG. 22 e shows aslightly variant configuration of clot engagement features of theengaging basket 471 having two-layer structure 478. The outer layer issmooth and atraumatic so that it can safely contact the artery wall,while the inner layer is shaped with clot indentation features 480 togrip and hold the clot. In another embodiment some or all of the clotretrieval device is coated with a clot adhering agent, which isconfigured to bond to unused active sites on the fibrin strands of theclot. In yet another embodiment the surface of the struts may betextured by roughening, knurling, flocking or similar means to provideenhanced grip of the clot. This surface modification may be applied toall strut surfaces, but is preferably applied to those surface notconfigured to contact the wall of the vessel.

The preferred orientation of above clot indentation features isdescribed in FIGS. 23 a-23 f.

FIG. 23 a shows a tube 501 from which engaging basket 502 has been lasercut. The tube may be of a size similar to the fully expanded diameter ofthe engaging basket, or of a size similar to the desired wrappeddelivery profile, or of an intermediate size.

FIG. 23 b shows an isometric view of struts 503 of the expanded engagingbasket. In one embodiment clot gripping features 504 protrude fromproximally facing surfaces 518, but not from vessel contacting surface516 or distally facing surface 517.

FIG. 23 d, e and f show a section view A-A through strut 503 of FIG. 23b with progressively greater amounts of polishing, demonstrating howgreater amounts of material removal can round edges 506 and create amore atraumatic vessel contacting surface 516. Thus polishing can beused to remove edge and surface material to create a smooth vesselcontacting surface without significantly affecting the efficacy of theclot engaging features.

FIG. 23 c shows another section view A-A through strut 503 of FIG. 23 b,this time including a view of vessel 511 in which it is expanded. Theradius of curvature R2 (514) of the strut section 512 and clot grippingfeature 513 is smaller than the radius of curvature R1 (515) of thevessel if the diameter of tube 501 from which the engaging basket wascut is smaller than the diameter of the vessel. This curvaturedifference helps avoid contact between the clot gripping feature and thevessel wall.

Another preferred embodiment of an engaging basket 551 with an innertubular member 553 of the present invention is depicted in FIG. 24 a-24c. The engaging basket 551 has an outer member 552 having a plurality ofstruts 557 and an inner braided tube 553 having one end attached to theouter member at a proximal junction 554 and other end attached to thestruts 557 at a distal junction 555. The inner braided tube is made ofnitinol fibres or stainless steel or other metallic fibres, or could bemade from a high strength polymer such as PET, PEN, LCP, aramid orUHMWPE. The fibres 556 of the inner braided tube 553 are attached to theouter member 552 through eyelets 558 in the struts 557 at distaljunction 555.

FIG. 25 a-25 d shows slightly variant configurations of attaching fibres573 at the distal junction 555. The struts 571 at the distal junctionare having oval eyelets 572 through which fibres 573 can be threaded.Alternatively, the struts 574, 576, 578 at the distal junction arehaving inflexions 575 or recesses 577 or bosses 579 through which fibres573 can be threaded.

Another preferred embodiment of an engaging basket 601 of the presentinvention is shown in FIG. 26 a. The engaging basket 601 has an outermember 602 and a plurality of integral capture nets 603.

Another preferred embodiment of an engaging basket of the presentinvention is shown in FIG. 26 b. The device comprises an elongate member611 connected to an expandable body 612 with a plurality of inletopenings 613 and a plurality of restraining layers 615 defining aplurality of reception spaces 614. In one embodiment the restraininglayers comprise mesh layers, and may be braided or knitted or formedfrom porous membranes. In another embodiment the restraining layerscomprise strut elements.

FIG. 27 represents another preferred embodiment of an engaging basket621 having an outer member 622, an inner tube 623 and integral capturenet 624.

Another preferred embodiment of an engaging basket 641 of the presentinvention is shown in FIGS. 28-29. The engaging basket 641 is attachedto a basket shaft 645 and has an outer member 642 and a detachabledistal capture net 643 attached to a distal capture net shaft 644. Thedetachable distal capture net 643 is attached to outer member strut 663and has a capture net 661, a capture net frame 662 and engagement tabs664, 665. Thus the capture net and its frame form an integral part ofthe engaging basket and may be used as such if desired by the user. Ifparking space distal of the clot is sufficient the capture net 643 maybe left distal of the clot to capture any released fragments while theouter member 642 is retracted with the clot.

Another preferred embodiment of an intracranial stent-platform basedclot retrieval device 681 of the present invention is shown in FIG. 30.The clot retrieval device 681 has an elongate shaft 689 having a distalend that extends interior of the artery and a proximal end that extendsexterior of the artery, an engaging basket 682 configured at the distalend of the elongate shaft 689 having an outer member 684 and an innerbraided tubular member 685 having proximal portion connected to theouter member 684 at a proximal junction 690, and a distal capture net683 attached to a distal capture net shaft 688 at a distal end whileproximal end extends exterior of the artery. The distal capture net 683has a capture net 686 mounted on frame 687. The distal capture net shaft688 runs through the elongate shaft 689 to enable the physician tomanually control and move the distal capture net 683 and engaging basket682 independently.

The outer member may be a laser cut nitinol member and be configured asshown in any of the other figures herein, and may have regions oftailored radial force as described in FIG. 47, 48 or 49.

FIGS. 31 a-31 e illustrates various designs for distal capture nets 702,704, 706, 708 and 710 and frames 701, 703, 705, 707 and 709 that couldbe used in place of the independent capture nets of the presentinvention. The nets could be knitted or braided from many metallic orpolymer monofilament or multifilament fibres, but are preferably madefrom SS, MP35N, Nitinol, Tungsten, PEN, PET, UHMWPE, LCP, or Aramidfibres. These fibres may be attached to the capture net frames at aplurality of attachment points 711, and said attachment points maycomprise any of the designs disclosed in FIGS. 24 and 25. The frames arepreferably self expanding and are preferably made from a superelastic orshape memory material such as nitinol, so that they can expand from acompressed delivery configuration to appose the wall of a broad range ofvessel sizes.

Another preferred embodiment of a clot retrieval device of the presentinvention is shown in FIGS. 32 a-32 c. The clot retrieval device isdesigned particularly for short parking space which is achieved bydesigning an ultra low profile capture net 754 that can be wrapped underthe engaging basket 753 while delivery through a microcatheter 751. Theclot retrieval device has an elongate shaft 752 having a distal end thatextends interior of the artery and a proximal end that extends exteriorof the artery, an engaging basket 753 configured at the distal end ofthe elongate shaft 752, and a capture net attached to a capture netshaft 755 at a distal end while proximal end extends exterior of theartery. The distal capture net shaft 755 run through the elongate shaft752 to facilitate the physician to manually control and move the distalcapture net 754 and engaging basket 753 independently.

Another preferred embodiment of a clot retrieval device of the presentinvention is shown in FIG. 33. The clot retrieval device has an elongateshaft 771, an engaging basket having an inner tubular member 774 madefrom a laser cut tube, an outer member having a plurality of ringelements 775 connected to a pair of axial ribs 773, and a distal capturenet 776. Axial ribs 773 are attached to the elongate shaft 771 byconnecting arms 772. The axial ribs preventing foreshortening of theengaging basket, thus minimizing axial compression of the clot. Thesetwo ribs will also align themselves with the axis of the vessel whenplaced in tension in tortuousity, allowing the ring elements to remainexpanded and in contact with the vessel walls, If the circumference ofeach half-ring is equal to or greater than that of the vessel in whichit is deployed, then they will be able to maintain wall apposition (in asimilar manner to that illustrated in FIG. 14 d) even if the axial ribsare pulled together against one wall of the vessel as may occur when thedevice is retracted against resistance through tortuousity. This ribbeddesign of outer member may also be employed as an inner tubular member.In one embodiment of a clot retrieval device both the outer member andinner members comprise ribs and rings similar to ring elements 775 andrib elements 773, and the ribs of both inner and outer members arealigned in the same plane which is naturally inclined to self-align tothe plane of bending, making the device highly flexible and maintainingan open lumen through the inner tube as well as good wall apposition ofthe outer member in bends and in tension. In another embodiment the ribsof the inner and outer members are 90 degrees offset from each other.

FIG. 34 represents another preferred embodiment of a clot retrievaldevice of the present invention. The clot retrieval device has anelongate shaft 791, an engaging basket attached to the elongate shaft791 having an inner tubular member 794 and an outer member 792 withplurality of inlet mouths 793, and a distal capture net attached to theinner tubular member 794 by connecting arms 795. The distal capture nethas a capture net 797 mounted on a frame 796.

Another preferred embodiment of an intracranial stent-platform basedclot retrieval device 881 of the present invention is shown in FIGS. 35a-35 e. The clot retrieval device 881 has an a shaft having a distal end890 that extends interior of the artery and a proximal end 893 thatextends exterior of the artery, an activation cable 884 that runsthrough said shaft and protrudes from both ends, a plurality of tubularcollars 885, a plurality of segments 886 attached to tubular collars885, and a distal stop 888. Each segment has circumferential struts 883and radial struts 882. The clot retrieval device 881 is advanced througha microcatheter 889 in a relatively straight and collapsed configurationacross the clot 892. Once deployed, the microcatheter 889 is retractedto allow the clot retrieval device 881 to reach the expandedconfiguration. The activation cable 884 is used to exercise radial forceto assist segments 886 to trap and engage the clot. The tubular collars885 and distal stop 888 are used as limit stops to prevent the clotretrieval device 881 from being overly compressed.

FIG. 35 a shows an isometric view of the device in a partially expandedstate.

FIG. 35 b shows the device compressed for delivery through amicrocatheter 889.

FIG. 35 c shows a side view of the device in a fully expanded state inwhich activation cable 884 has been placed in tension and shaft 890placed in compression so that tubular collars 886 and distal collar 887are brought together by the action of cable stop 888, which assists theexpansion of segments 886. In one embodiment segments 886 are fully selfexpanding, and are simply assisted by the actuation mechanism. Inanother embodiment the segments are configured to self expand to adiameter less the fully expanded diameter, and in yet another embodimentthe segments are not self expanding at all and are fully driven by theactuation mechanism.

FIG. 35 d shows the device deployed within a clot prior to actuation ofcable 884. The low, atraumatic radial force of the self expandingsegments is not sufficient to embed the struts of the segment in theclot to any significant degree.

FIG. 35 e shows the device deployed within a clot post actuation ofcable 884. The middle segment has been compressed and assisted inexpanding and displacing the clot.

This principle of operation is applicable to all the actuatable designsdisclosed herein, and is intended to be combined with all of theelsewhere disclosed engaging basket features, such as inlet mouths,scaffolding regions, reception spaces, stepped diameters, variableradial force, inner tubular members and capture nets.

Thus this Engager design is self expanding, but can be given extra helpby actuation of the activation cable. This is useful because it allowsthe user to apply some extra radial force to the engager immediatelyafter it is deployed under the clot, which will assist the engager inembedding itself into the clot, and urging the clot into the engagerbody. The tubular collars are used as limit stops to prevent the devicefrom being overly compressed. The fact that the device is self expandingmeans that the user can release the actuation cable once the clot hasbeen engaged, and the engager will continue to stay engaged with theclot, but at a lower radial force. This lower force is high enough toretain a grip on the clot while it is withdrawn through the vasculature,but is low enough to ensure that no trauma is caused to the vessel.

This concept can be used as a standalone engager as shown, or can beused as an internal expansion aid inside an outer engager body, as shownin FIGS. 40-42.

The actuation cable may be fixed to the distal collar of the device, ormay have a distal stop as shown which can engage with the distal collarwhen pulled. If used with a distal stop the actuation cable may be usedas a guidewire/re-access wire as disclosed elsewhere in this document. Abasket could also be attached to the distal end of the actuation cableas disclosed elsewhere in this document

Another preferred embodiment of a clot retrieval device of the presentinvention is shown in FIG. 36. The clot retrieval device has anactuation cable 951 having a plurality of stops 953, a shaft 956, anengaging basket 954 having a plurality of actuation struts 955protruding inwardly, a safety stop 958, a distal tip 952, and a capturenet 957. The stops 953 are used to apply compression force on actuationstruts 955 which imparts expansion force to the engaging basket 954. Theexpansion force facilitates to create a flow lumen through the clot andassist the migration of the actuation struts 955 through the clot togrip the clot effectively without the need for significant radial force.

FIG. 37 represents a clot retrieval device of the present inventionwhich is similar in principle to the clot retrieval device shown in FIG.35. The clot retrieval device has an actuation cable 971 having aplurality of stops 973, a shaft 977, a plurality of engaging basketsegments 97, a connecting strut 975, a collar 976, a distal collar 978,a proximal collar 979, a distal tip 972, and a stop 973.

FIG. 38 represents an intracranial stent-platform based clot retrievaldevice of the present invention which is yet another slightly variantembodiment of the clot retrieval device as shown in FIGS. 36 and 37. Aclot retrieval device has an actuation cable 991, a shaft 992, aplurality of smaller diameter inner segments 999 having shorter struts995 to create a flow lumen through the clot and facilitate restorationof blood flow immediately after the clot retrieval device is deployedacross the clot, and a plurality of larger diameter outer segments 998having longer struts 994 to accommodate a broad artery size range andallow clot retrieval device to retain the clot while withdrawing intoprogressively larger diameter proximal arteries, and a distal joint 997.The most proximal outer segment 998 is attached to the shaft 992. Thespace between the outer segment 998 acts as inlet mouths to trap andengage clot without exercising excessive compression force on clot.

FIGS. 39 a-e show a clot retrieval device in which a region of theengaging basket can be compressed in the axial direction in order toexpand it in the radial direction. This is achieved by compressing a setof struts that project radially inward from the outward member. Thedevice comprises an elongate tubular shaft 1052 having a distal end thatextends interior of the artery to which is fixed a collar 1053 and aproximal end that extends exterior of the artery, an actuation cable1051 that runs through and protrudes from either end of said shaft, anexpandable outer member that is slidably attached to the distal end ofshaft 1052 and comprises at least one set of inwardly and proximallyfacing struts 1057 and at least one set of inwardly and distally facingstruts 1058, a transfer tube 1054 and a capture net 1061. The transfertube lies between the distal collar 1053 and the inwardly facing strutsand is sliceable over the distal section of the actuation cable. Theapplication of tension to the actuation cable and compression to theshaft applies compression to the inwardly facing struts which servesimpart an outward radial expansion force to the distal end of the outermember. In the embodiment shown the proximal collar is free to slide onthe shaft, and is limited by a stop (1053) from sliding distally beyondthe stop. This freedom allows the engaging basket to foreshorten as itexpands as shown in FIG. 39 d. In another embodiment of this design theproximal collar (1056) of the engaging basket is fixedly attached to theshaft (1052).

FIG. 39 b shows a close-up of the region of the engaging basket in whichthe inwardly facing struts are located, with the net and actuation cableremoved for clarity. Inwardly facing struts 1057 and 1058 are joined toouter member 1055 at point 1062. In other embodiments these struts maybe spaced further apart, so that at least one strut element of member1055 is also placed in compression when the inwardly facing struts arecompressed.

FIG. 39 c shows the device as configured for delivery. The shaftdelivers push to the engaging basket through transfer tube (1054) andstruts (1057).

FIG. 39 d shows the device being actuated. The cable 1051 is tensioneduntil stop 1060 reaches the end of transfer tube 1054.

FIG. 39 c shows the device as configured for withdrawal from the vessel.Shaft 1052 is retracted, which causes stop 1053 to contact proximalcollar 1056, which places the engaging basket in tension for saferetrieval.

FIG. 40 represents shows a clot retrieval device of the presentinvention which is largely similar to the clot retrieval device 881 asshown in FIG. 35, the only difference is addition of an outer member1081.

Another preferred embodiment of a clot retrieval device of the presentinvention is shown in FIG. 41. The clot retrieval device has an elongateshaft 1104 having a distal end that extends interior of the artery and aproximal end that extends exterior of the artery, an engaging basketconfigured at the distal end of the elongate shaft 1104 having an outermember 1102, and an expander 1101 attached to an expander shaft 1104.The expander 1101 is withdrawn through the outer member 1102 to assistits expansion and create a flow lumen through the clot retrieval deviceand clot. Alternatively, there can be plurality of expanders 1101connected in series.

Another preferred embodiment of a clot retrieval device of the presentinvention is shown in FIG. 42. The clot retrieval device has an elongateshaft 1123 having a distal end that extends interior of the artery and aproximal end that extends exterior of the artery, an engaging basketconfigured at the distal end of the elongate shaft 1123 having an outermember 1122 and a braided inner expandable member 1121 with one endconnected to outer member 1122 at connection point 1125, and a capturenet 1126. Alternatively, there can be plurality of shorter braidedmembers.

FIG. 43 a-43 f illustrates various means of rendering intracranialstent-platform based clot retrieval device of the present inventionvisible under fluoroscopy (x-ray) using materials of a high atomicnumber and density. The clot retrieval device visibility can be achievedby surrounding strut 1151 by coiled wire 1152. A tab 1155 can be weldedto a crown 1159 or eyelet 1157 with tab 1155 riveted or welded or bondedinside. A coating 1158 applied to one or all surfaces. The surface areamay also be increased by adding a tab 1155 to a crown 1159 or increasingstrut width in certain areas. Alternatively, a tab 1160 protruding froma crown 1159 can be sleeve/marker band 1153 or coil mounted 1154.

Another preferred embodiment of an intracranial stent-platform basedclot retrieval device of the present invention is shown in FIG. 44 a-44h. A guidewire 1184 and microcatheter 1183 are inserted in the artery1181 and are advanced across the obstructive clot 1182 using anyconventionally known techniques. The guidewire 1181 is removed from theartery 1181 to allow the clot retrieval device be advanced through themicrocatheter 1183 in a collapsed configuration until the distal capturenet 1185 reaches distal of the clot 1182. The microcatheter 1183 isretracted to deploy the clot retrieval device across the clot 1182 in amanner that the capture net 1185 is positioned distal of the clot 1182and engaging basket 1186 is positioned across the clot 1182. In a firstpass, only a portion of clot 1182 is captured by the engaging basket1186. The portion of captured clot 1190 and engaging basket 1186 isretracted by engaging basket shaft 1187 and withdrawn into a guidecatheter (not shown), leaving the remaining clot portion 1189 inside theartery 1181. The capture net 1185 attached to capture net shaft 1187remains in its original position. A microcatheter 1183 is readvancedacross the remaining clot 1189 using capture net shaft 1187 as an accesswire. An engaging basket 1186 is advanced through the microcatheter 1183across the remaining clot 1189 and retracted again to remove theremaining clot 1189. The capture net 1185 is then removed along with anycaptured fragments. The capture net shaft in this example acts as anintegral access wire. Such an access wire may be either:

-   -   short with no extender, to allow the engaging basket to be        withdrawn as far as the guide catheter and readvanced multiple        times.    -   Short with extender, to allow the engaging basket to be        withdrawn completely and then reused or other device used, or to        simply allow the exchange of another device such as a        microcatheter over the device.    -   Long (with or without mid-length detachment facility) to allow        the engaging basket to be withdrawn completely and then reused        or other device used, or to simply allow the exchange of another        device such as a microcatheter over the device.    -   Any of above with a basket on the end of the wire (as shown).    -   Any of above with a stop on the wire for use with actuatable        designs disclosed elsewhere in this patent.

FIG. 45 shows a graph 1251 of the results of testing that was carriedout to investigate how certain properties of clot change when the clotis compressed. The test involved applying force to sample clots tosimulate the compression they might see during clot retrieval, whichresulted in significant dehydration of the clots. The effect of this onthe frictional properties of the clot was then measured by placing theclot on an inclined plane and increasing the angle of inclination untilthe clot began to slide down the plane. The vertical axis 1252 is thetangent of the angle at which the clot began to slip and the horizontalaxis 1253 is the percentage dehydration of the clot. Samples of porcineblood were collected for this purpose and coagulated into clotspontaneously (clot type A, represented by diamond shape 1254 in thegraph) and with the aid of thrombin (clot types B, represented bytriangular shape 1255 in the graph and clot type C, represented bysquare shape 1256 in the graph). Each of the three different clot typeswas then tested as follows:

Each clot sample was weighed and then placed in a tapered funnel whereit was gently compressed by the force of its own weight, allowingliberated fluid to escape through the funnel orifice. The clot was thenremoved from the funnel, weighed again to establish the level ofdehydration, and placed in the test fixture. The test fixture consistedof a wetted planar surface which could be inclined at varying degrees tothe horizontal. The angle of the plane was then gradually inclined fromhorizontal until the clot began to slide down the plane. The coefficientof friction for the purposes of this study was defined as the tan of theangle at which sliding commenced.

This test was repeated with each of the three clot types describedabove, and at various different levels of dehydration. The results wereplotted in the graph presented in FIG. 45. In summary, at 25%dehydration the tested clots showed on average an increase ofapproximately 40% in their coefficient of friction. These surprisingresults show that compressing (and thus dehydrating) clot can result ina significant deterioration in frictional properties and hencesignificantly increase the force required to remove it from a bloodvessel.

FIG. 46 depicts another clot retrieval device of this invention deployedwithin a clot 1307 in a vessel 1308. The clot retrieval device comprisesan elongate member 1309 configured to extend from exterior of thepatient to the target clot retrieval site interior of the patient, anexpandable body 1312 connected at its proximal end to a distal sectionof the elongate member 1309 with a wall 1308 containing multiple inletopenings 1310 and scaffolding areas 1311, an inner tubular body 1304situated within the expandable body and running substantially the lengthof the expandable body, and a capture net 1305 at the distal end of theexpandable body. The clot retrieval device is deployed within the clotwith a first segment 1301 generally proximal of the clot, a secondsegment 1302 generally within the clot and a third section 1303generally distal of the clot. In this way the first segment preventsproximal movement of the clot, the third segment prevent distal movementof the clot and the middle segment grips the clot by virtue of thescaffolding sections applying pressure to the clot which urges portionsof the clot to migrate through the inlet openings in the wall into aninternal reception space. The inner tubular member defines a lumenthrough this space through which blood can flow through the clot,relieving the pressure gradient across the clot, which reduces the forcerequired to dislodge and retrieve the clot. The distal capture net isconfigured to catch any fragments that may be released which mightotherwise cause distal embolization. One of embodiment of the structureof the expandable body, inner tubular member, capture net and elongatemember are depicted here, but it is intended that any of the structuresdepicted elsewhere in the disclosure may be applied also.

FIG. 47 depicts a developed view of the expandable body 1355 of anotherclot retrieval device of the invention. The features described hereincould be applied to any of the expandable bodies described elsewhere.Other features such as inner tubular members and capture nets may thusbe employed with this expandable body but are omitted from this figurefor clarity. Expandable body 1355 comprises a proximal segment 1356, amiddle segment 1357 and a distal segment 1358, each segment connected atconnection points 1365 and 1366. A proximal connecting arm 1368 isconnected to the proximal end of the proximal segment to provide a meansof attachment to an elongate shaft (not shown). Each segment comprisesmultiple struts, any of which may comprise clot gripping features 1367,which are described in more detail in the detailed description relatingto FIGS. 22 and 23. The struts and crowns of each segment are designedto exert different degrees of radial force in different regions. Theresultant radial force gradient assists in urging the clot into theinlet openings, and in holding it securely once there. The expandablebody comprises multiple strut geometries—strut type A 1359 is arelatively stiff strut, strut type C 1361 is a relatively flexible strutand strut type B 1360 is a tapered strut of a stiffness between that ofA and C, and multiple crown geometries—crown type A 1362 is a relativelystiff crown which imparts a significant radial force to its neighbouringstruts, crown type B 1363 is a more flexible crown and crown 1364 is aterminal crown that is not distally connected to a strut. Proximalsegment 1356, middle segment 1357 and distal segment 1358 utilise theaforementioned stiffer struts and/or crowns to create high radial forcerings adjacent the proximal end of each segment. In other embodimentsthe expandable body may be formed from multiple segments similar to anyone of the above three segments, or may be formed from a mix ofsegments. In one embodiment the expandable body does not have inletopenings but does have a series of radial force gradients which compriseregions of high radial force and regions of low radial force. Theregions of low radial force act as effective reception spaces for theclot as it is urged towards these regions by the high radial forceregions. The radial force may also be varied around the circumference ofthe expandable body using similar means or by adjusting strut lengths.

FIG. 48 a, b, c and d show another clot retrieving expandable body 1401of this invention with a two stage radial force system. The featuresdescribed herein could be applied to any of the expandable bodiesdescribed elsewhere. Other features such as inner tubular members andcapture nets may thus be employed with this expandable body but areomitted from this figure for clarity. FIG. 48 a depicts expandable body1401 deployed within a clot 1409 in a vessel 1410. Expandable body 1401comprises a series of connected rings of a generally cylindrical shapeconnected at junction 1404 by proximal struts 1403 to connector arm1402, which is connected to an elongate member (not shown) extendingexternal of the patient. The rings comprise a network of struts andcrowns which are better described in FIGS. 48 b, c and d and whichinclude markers 1408 at the distal end for visibility under fluoroscopy.In the deployed condition within a clot in a vessel the rings of theexpandable body may be highly compressed such as ring 1407, partiallycompressed such as ring 1406, or uncompressed such as ring 1405 orcompressed to any level between these.

In order to grip the clot firmly it is desirable for the struts of theexpandable body to migrate into the body of the clot upon or shortlyafter deployment, and thus it is desirable that the expandable body canexert a high radial force when compressed to a small diameter within theclot. However it is also desirable that the expandable body exert a lowradial force on the vessel walls through which it must be retracted inorder to avoid vessel trauma. This conflict may appear to be addressedby a conventional stent-like clot retriever strut pattern, as the radialforce of the device increases the more it is compressed. However such adesign provides a generally linear progression in radial force betweenexpanded and compressed states, which means that if the radial force inthe compressed state is increased to a sufficient level to effectivelygrip firm clots it may be too high to safely move through thevasculature, even when doing so in larger diameter vessels. This problemis overcome by the disclosed design because it allows the expandablebody to exert a high radial force when compressed to a small diameterand another much lower radial force when compressed to a lesser degreein a larger vessel.

FIG. 48 b shows a ring of expandable body 1401 from FIG. 48 a compressedto a diameter D1 1438 as it might be for delivery through amicrocatheter. Crowns 1481 are connected to stiff strut sections 1432which are in turn connected to flexible strut sections 1433 bytransition sections 1437. Strut opening angles α1 1435 and β1 1436 atcrowns 1434 and 1431 respectively are generally similar in this highlycompressed state.

FIG. 48 c shows ring 1407 of FIG. 48 a and the ring of FIG. 48 bcompressed to diameter D2 as it might be when deployed within a clot.The higher radial force of the stiffer struts and crowns drives theexpandable body firmly into the clot such that the opening β2 1453between the stiff struts is higher than strut opening angle α2 1452between the flexible struts.

FIG. 48 d shows ring 1405 of FIG. 48 a and the ring of FIGS. 48 b and cexpanded to diameter D3 1471 as it might be when deployed within avessel of diameter close to the fully expanded diameter of theexpandable body. The opening β3 1473 between the stiff struts issubstantially the same as opening angle β2 in FIG. 48 c but the openingangle α3 1472 between the flexible struts is greater than strut openingangle α2 1452 from FIG. 48 c. Thus the opening force that drives theexpandable body to expand from a clot gripping diameter of approximately50% or less of its fully expanded diameter to a fully expanded diameteris primarily driven by the flexible strut and crown members, and theopening force that drives that drives the expandable body to expand fromits delivery state to a clot gripping diameter of approximately 50% orless of its fully expanded diameter is primarily driven by the stiffstrut and crown members, so that a high radial force can be applied togrip the clot without a high radial force being applied to the vessels.

In one embodiment as might be applicable for the retrieval of clots fromcerebral vasculatures diameter D1 may be 0.75 mm or less, diameter D2may be approximately 1.5 mm or 2 mm and diameter D3 may be approximately4 mm to 6 mm.

In another embodiment of the device shown in FIGS. 48 a-d the crown andstrut design of each ring is more symmetrical in nature, with each struthaving a flexible mid section and a stiffer section at each end adjacentits crowns. The flexible mid strut section is configured to adopt an “S”shape to increase the diameter of the expandable body at a low radialforce beyond the clot gripping preset diameter of the stiff strutcomponents.

FIG. 49 shows a ring 1501 of an expandable body of this invention whichis configured to deliver a two stage radial force somewhat similar tothat of the design shown in FIG. 48. The ring may be a nitinol ring cutfrom a tube or sheet. In this case the ring comprises stiff struts 1504connected to one another at crowns 1506, and flexible struts 1505connected to one another at crowns 1508. Alternating pairs of stiff andflexible struts are connected at crowns 1507. In one embodiment in theexpanded state the opening angle 1502 of crowns 1506 is lower than theopening angle 1503 of crowns 1509. In this way the device will exert alow outward radial force when compressed by up to 50% or more of itsexpanded diameter as the flexible strut and crown elements will take thebulk of the applied strain, but will exert a high radial force whencompressed significantly below 50% of its expanded diameter as strainwill then be induced in the stiffer struts and crowns.

FIG. 50 shows another embodiment of a clot retrieval device of thepresent invention. The clot retrieval device 1551 has an elongate shaft1553 having a distal end that extends interior of the artery and aproximal end that extends exterior of the artery, an inner cable 1557with a distal tip 1561 that extends through the elongate shaft, and aseries of expandable segments 1568, 1566 and 1563. Proximal expandablesegment 1568 is connected to elongate shaft 1553 at collar 1554, and tomiddle segment 1566 by axial connectors 1567. Middle segment 1566 isconnected to distal segment 1563 by axial connectors 1567, and isslidably attached to core wire 1557 at collar 1565 by stop 1559. Distalsegment 1663 is also slidably attached to core wire 1557 at anothercollar 1565 by stop 1560. Each segment comprises multiple struts 1555and crowns 1552, including terminal crowns 1556 to which the axialconnectors are joined. The middle and distal segments have distal arms1558 and 1562 respectively which run radially inward from the body ofthe segment to its distal collar. These distal arms enable a compressiveload to be applied on these segments by applying a tensile load to theinner cable, which transmits this load through stops 1559 and 1560 tocollars 1565 and hence through the distal arms to the segments. Thiscompressive load can be used to temporarily increase the opening forceor radial force of the segments, which allows the user to dial up thedevice radial force to achieve strong clot engagement and then relax thetension in the inner cable to return the device to a low radial forcestate for atraumatic removal through the vasculature. The axialconnectors 1567 are preferably long, slender and flexible, ideallyhaving a length to width aspect ratio in excess of 20:1 so that they actas flexible tethers between each segment. In this way they providearticulation regions which allow the device to accommodate highlytortuous vessels without either deforming the expanded device shape(which is important for retaining a grip on captured clot) or exerting ahigh lateral force on the vessel wall (which is important for avoidanceof trauma). The connector arms also provide atraumatic transitions tothe proximally facing terminal crowns which might otherwise snag orabrade the vessel wall during withdrawal. Another benefit of theconnector arms is that they create reception spaces between segments forclot entrapment and retention, and by virtue of their flexibility theycreate effective regions of low radial force between the higher radialforce segments, which combine to urge the clot into the receptionspaces.

FIGS. 51 a and 51 b show another embodiment of a clot retrieval deviceof the present invention. The clot retrieval device 2027 has an elongateshaft 2026 having a distal end that extends interior of the artery and aproximal end that extends exterior of the artery and of the body, aninner tubular member 2028 and an outer member 2029. The inner and outermembers are preferably made of a superelastic or pseudoelastic materialsuch as Nitinol or another such alloy with a high recoverable strain.Shaft 2026 may be a tapered wire shaft, and may be made of stainlesssteel, MP35N, Nitinol or other material of a suitably high modulus andtensile strength. Shaft 2026 has a sleeve 2001 adjacent its distal endand proximal of the outer member and inner tubular member. This sleevemay be a metallic coil and may be formed from stainless steel or from amore radiopaque material such as platinum or gold for example or analloy of such a material. In another embodiment this sleeve may bepolymeric, and may be rendered radiopaque through the addition of afiller material such as tungsten or barium sulphate. Shaft 2026 may haveintegral collars or step features 2002 and 2003 to assist the integrityof the joints between the distal end of the shaft and the proximal endsof the inner tubular member 2028 and the outer member 2029. The proximalend 2004 of the outer member and proximal end 2020 of the inner tubularmember may comprise collars and said collars may comprise one or moreelastic regions so that they can be assembled onto the shaft 2026proximal of step features 2002 and 2003, such as in the manner of asnap-fit joint. In other embodiments the proximal collars may be splitor may have other locating features to facilitate a strong joint to theshaft. In some embodiments one or both of these joints comprise asolder, braze or adhesive joint, while in another they may comprise aweld joint. In yet another embodiment one or both collars are rotatableon the shaft, and may be configured to slide along the axis of the shaftbetween limit stops.

Outer member 2029 comprises proximal struts 2005 connected at theirproximal ends to collar 2004 and at their distal ends to a firstexpandable member 2030, which is in turn connected to a secondexpandable member 2031 by two connecting arms 2011, which run from aproximal junction 2010 to a distal junction 2012. In one embodimentthese connecting arms comprise generally straight struts runningparallel to the central axis of the device. In other embodiments theseconnecting arms may comprise a plurality of struts configured in one ormore cells, or may comprise curved or spiral arms. The region betweenthe first and second expandable member comprises two inlet mouths 2013through which clot may pass and enter the reception space defined by theregion between the inner and outer members. The closed end of the secondexpandable member prevents the egress of clot or clot fragments thathave entered said reception space. The outer member is configured toself-expand upon release from a restraining sheath (such as amicrocatheter) to a diameter larger than that of the inner tubularmember and functions in a manner similar to that described for outermember 8 of FIG. 1 a.

The first expandable member comprises a series of interconnected struts,with certain struts such as strut 2006 terminating in crowns with nodistal connecting elements, and other struts such as 2008 terminating injunction points such as 2009 and 2010. The second expandable member 2031comprises a series of interconnected struts, with certain struts such asstrut 2014 terminating in crowns with no distal connecting elements, andother struts such as 2015 terminating in junction points. One or bothexpandable members may comprise marker bands or radiopaque features suchas disclosed in detail in FIGS. 43 a-f. The distal end of the secondexpandable member comprises a series of struts 2016 and 2017 thatultimately terminate at a distal junction point 2018, thus defining aclosed end to the outer member. This series of struts may comprise agenerally conical shape as shown in FIG. 51 a, or in other embodimentsmay comprise a generally flat plane which may be inclined or may benormal to the longitudinal axis of the device. In one embodiment (asshown) the distal junction point 2018 comprises a collar. Struts 2016and 2017 may be tapered to a narrower width than those of the moreproximal struts comprising the body of the first and second expandablemembers, thus creating a gradual transition in the stiffness of thedevice both in the expanded and collapsed states. In certain embodimentsthis distal section may comprise fibre attachment points such as eyeletsor any of the other fibre attachment features described elsewhere inthis document, and in yet other embodiments fibres may be connected tothe distal section at these attachment points to create a distal net asshown in several other figures.

Inner tubular member 2028 comprises a generally cylindrical section ofinterconnected struts 2022, which is connected at its proximal end bystruts 2021 to collar 2020, and at its distal end by struts 2023 tocollar 2024. In one embodiment (as shown in FIG. 51 b, which is aclose-up, partially sectioned view of the distal end of the device ofFIG. 51 a) the distal end of the inner tubular member also comprises acoil section 2032 and a distal arm 2033. This coil and arm may be lasermachined from the same tube from which the rest of the inner tubularmember is processed. A radiopaque coil (which could be platinum gold oran alloy of same) is positioned over the distal arm 2033 and runs underthe distal collar 2018 of the outer member 2029, where it is connectedby a solder joint 2019 to the collar 2018 and arm 2033.

In other embodiments the inner tubular member may not be connected tothe distal end of the outer member at all, or may be constrained withinthe outer member without being fixedly attached as disclosed elsewhereherein. In other embodiments the inner tubular member may have anon-cylindrical cross-section, may be non-uniform in diameter, and mayhave tailored strut patterns to provide regions of differing radialforce or flexibility. Inner members of such designs are disclosedelsewhere in this document and it is intended to be understood thatthese may be combined with any of the outer members disclosed herein,even though not all of these combinations may have been illustrated. Therole of the inner member is described in more detail in the detaileddescription pertaining to FIGS. 53 to 57.

FIG. 52 a shows another embodiment of a clot retrieval device of thepresent invention. The clot retrieval device 2101 has an elongate shaft2109 having a distal end that extends interior of the artery and aproximal end that extends exterior of the artery and of the body, aninner tubular member 2117 and an outer member 2122. Shaft 2109 has asleeve 2102 adjacent its distal end which is similar to sleeve 2001 ofdevice 2027.

Outer member 2122 comprises three expandable sections 2104, 2105 and2106 and is configured to expand within and/or proximally and distallyof the clot and function in a manner similar to that described for outermember 8 of FIG. 1 a. The outer member may comprise marker bands orradiopaque features such as disclosed in detail in FIGS. 43 a-f. Firstexpandable section 2104 is very similar to member 2030 of FIG. 51 a, andis connected to second expandable section 2105 by two connecting arms2110, which run from connection points 2012 to connection points. Secondexpandable section 2105 is similar to 2104, and is connected to thirdexpandable section 2106 by two connecting arms 2111, which run fromconnection points 2114 to connection points 2115. Connecting arms 2111are 90 degrees offset from connecting arms 2110. Third expandablesection 2106 is similar to member 2031 of FIG. 51 a, and comprises agenerally cylindrical scaffolding region and an inwardly tapering distalregion 2123. Region 2123 comprises elements which project into andacross the lumen of the vessel in which the device is deployed, and thusserve to prevent the distal migration of clot or clot particles that arecarried into that region. FIG. 52 b describes one embodiment of thisregion in more detail.

Inlet mouths 2120 and 2121 lie between scaffolding expandable sections2104 and 2105 and between 2105 and 2106 respectively, and are intendedto provide openings through which clot may be urged by the outwardradial pressure exerted by the surrounding scaffolding sections.

Outer member 2122 and inner member 2117 are connected to shaft 2109 byproximal collars 2103 and 2116 and distal collars 2118 and 2119respectively, which are rotatable on the shaft so that the distal tip2108 may be torqued or steered by the user without rotation of the outeror inner members simply by torquing the proximal end of shaft 2109. Inone embodiment the proximal collars are also configured to be slidable alimited distance between limit stops on the shaft, which allows theshaft to be moved a certain distance without imparting movement to theinner and outer members. Such a feature can be employed to make thedevice forgiving of unintentional movements of the shaft which mightotherwise cause inadvertent forward movement of the deployed orpartially deployed device.

Inner Tubular member 2117 is similar to item 2028 of FIG. 51 a andfunctions in a manner similar to that described for inner tubular member5 of FIG. 1 a. It comprises a generally cylindrical body section with aproximal termination 2116 which is connected to shaft 2109, and a distaltermination 2118 which is slidably connected to core wire 2107. In otherembodiments the inner tubular member may have an open distal end withouta singular terminal point, and may be unconnected at its distal end. Anumber of inner tubular member designs that may be assembled within anouter engager member to form an engaging basket or Stent-Basket aredisclosed elsewhere in this document, including in FIGS. 53 to 57.

FIG. 52 b shows one embodiment of the distal end of the device of FIG.52 a. A series of radially inwardly projecting struts are configured ina generally dome-like shape terminating in collar 2151, which in thisembodiment is slidably connected to core wire 2107, which itself isconnected to tip section 2108. In other embodiments, some of which areillustrated elsewhere in this patent, the inwardly projecting struts mayterminate at a point that is not a cylindrical collar, or may terminateat more than one point and may not be connected to a core wire. Theinwardly projecting struts create a scaffolding region to prevent thedistal migration of clot or clot particles that may travel towards thedistal end of the clot engaging device. The scaffolding may be furtherenhanced by the addition of fibres 2157 and 2158 which are connected tothe strut members at connection points 2155, wherein said connectionpoints may comprise eyelets or other shapes such as shown in FIGS. 24and 25, and said fibres may be looped through or around said connectionpoints and may also be tied or bonded in place. Fibres 2157 and 2158 maycomprise any of a range of metallic or polymer monofilament ormultifilament fibres, but are preferably made from SS, MP35N, Nitinol,Tungsten, PEN, PET, UHMWPE, LCP, or Aramid fibres.

In the embodiment shown in FIG. 52 b strut segments 2153 compriseproximal connection points 2152 which are connected to or form a part ofthe distal outer expandable member 2106. Strut segmented 2154 is taperedin width and is connected to curved strut section 2156. The curvature ofstrut sections 2156 creates a zone of controlled buckling which enablesthe distal dome-like section to deflect at a very low force ifcompressed. This is because proximal deflection of collar 2151 can beaccommodated by rotation of the collar, which is in accommodated bybending of strut section 2156 in a plane approximately normal to theaxis of the vessel and device, as opposed to bending in a planeapproximately parallel to the axis of the vessel and device as would bethe case with a conventional straight strut. If the strut has a width todepth aspect ratio of less than 1:1 then it will bend in this normaldirection at a lower force than it will bend in the perpendiculardirection. If strut segments 2156 are cut from the same tube or sheet asthe rest of the outer member, then the depth (or wall thickness) of thestruts 2156 is likely to be significantly greater than the width of thestruts, and thus providing this low force deflection mode maysignificantly reduce the likelihood of vessel injury caused if thedistal end of the device is inadvertently advanced.

One method of attaching the collar of an inner or outer member to ashaft is to use a snap-fit design such as illustrated in FIG. 52 c.Shaft 2171 has a stepped taper zone 2172 whose largest diameter islarger than that of the shaft proximal of it. Collar 2174 is connectedby connecting arms 2173 to outer or inner member (not shown), andcomprises flexible expansion elements 2175 which enable the innerdiameter of the collar to expand to a diameter at least equal to that ofthe largest diameter of stepped taper zone 2172. This constructionprovides a very robust connection between shaft and collar, and has theadded advantage of facilitating rotation of shaft relative to collar ifthe inner diameter of the collar is slightly greater than that of theshaft 2171.

A number of inner tubular member designs are disclosed in FIGS. 53 to57. It is intended that any of these designs may be combined with any ofthe outer member/outer engager designs disclosed elsewhere, or may beapplied to any of the inner tube designs illustrated elsewhere in thisdocument. A high radial force at small vessel diameters may be achievedin a very low profile inner tube by utilising short strut lengths andcutting from a small diameter tube. Thus the inner tubular member maywrap down to a profile that is lower than the lumen space left withinthe wrapped outer member, and hence have minimal negative impact on theoverall device wrapped profile. The inner tube can therefore be used toexert a strong opening radial force on the clot, restoring a flow lumenacross the clot and reducing the pressure gradient across the clot. Thiscontrolled, low diameter flow lumen can also serve to avoid a suddenharmful increase in pressure and flow to the distal neurovasculature,which might give rise to adverse events such as hemorrhagic conversion.The inner tube can be used to provide the clot retrieval device with astrong clot gripping force at small diameters to reliably grip anddislodge the target clot, while the outer member can be configured witha vessel friendly lower radial force as it simply needs to retain agentle grip on the dislodged clot for safe retraction to the receivingcatheter.

Any of the inner tubular members or outer members of this inventioncould be machined from a tube or from a sheet, or could be formed fromwire. Laser machining or water jet cutting or chemical etching could beemployed as machining methods. A super-elastic or pseudoelastic materialsuch as nitinol or a similar alloy is a preferred material choice forits self-expanding properties. It is intended that any of the outermembers disclosed herein may be combined with any of the inner tubularmembers and with any of the capture net/distal scaffolding constructionsand with any of the shaft designs also disclosed within this document.

FIG. 53 a shows a tubular member 3006 whose centreline follows agenerally helical path along at least a portion of its length. Thetubular body 3003 comprises a plurality of struts 3004 and is connectedto shaft 3001 by connecting arms 3002 at its proximal end. In theembodiment shown the distal end 3005 of body 3003 is open, but in otherembodiments it may be closed by inwardly facing struts, and in stillother embodiments it may flared radially outwards. A helical or spiralcentreline such as this may be applied to members of other crosssections also, such as those illustrated in FIGS. 53 c-g.

FIG. 53 b shows a tubular member 3025 with a dual tube configuration.Tubular bodies 3023 and 3024 comprise a plurality of struts 3026 and areconnected to each other and to shaft 3021 by connecting arms 3022 attheir proximal ends. In the embodiment shown the distal ends of bodies3023 and 3024 are open, but in other embodiments one or both ends may beclosed by inwardly facing struts, and in still other embodiments mayflared radially outwards.

FIGS. 53 c-g show a range of cross-sectional shapes of inner tubularmembers. FIG. 53 c is a cross-section of a tubular member whose outersurface 3041 is generally cylindrical in shape:

FIG. 53 d is a cross section through member 3025 of FIG. 53 b, in which3051 is the outer surface of tubular body 3023 and 3052 is the outersurface of tubular body 3024.

FIG. 53 e shows a cross-section through a member comprising threegenerally parallel tubular bodies 3061, 3062 and 3063, whose centrelinescould be straight or could be curved in a similar manner to that of body3006 in FIG. 53 a.

FIG. 53 f is a cross section through body 3072 which has a kidney shapedprofile with a folded region 3071 in its expanded form as shown. Body3072 comprises a generally cylindrical shape when wrapped in amicrocatheter for delivery, but expands out into the kidney shapedprofile shown when it is unsheathed. The folded region 3071 serves topinch and hold the clot into which it is deployed, while a flow lumen iscreated across the clot by the inner lumen 3073.

FIG. 53 g is a cross section through body 3082 which has a cloverleafshaped profile with folded regions 3081 in its expanded form whichfunction in a similar fashion to folded region 3071 of FIG. 53 f.

FIG. 53 h is a cross section through body 3091 which has a kidney shapedprofile in which an inner tubular member 3092 and an outer member 3093are formed from the same tube or sheet of material.

Any of the cross-section profiles disclosed in FIGS. 53 c-g could alsobe employed with any of the outer member/engager designs shownelsewhere, and the tubular members defined by these profiles could beused as standalone clot retrieval devices without additional outermembers.

FIG. 54 shows a developed view of a portion of an inner tubular member3101 representing some of the strut shapes and patterns that may beemployed to provide the member with the optimum combination of radialforce, wrapped profile and flexibility. Struts 3102 are shorter andwider than struts 3105, so that a first region comprising a plurality ofinterconnected struts 3102 has a higher radial force then a secondregion comprising a plurality of interconnected struts 3105. However thelonger and narrower struts 3105 of second region would give it greaterflexibility in both the wrapped and expanded configuration than thefirst region unless the first region were to comprise flexibleconnectors such as 3106 or unconnected crowns such as 3103. Taperedstruts 3104 are shown which may be employed to create a transitionbetween relatively high and low radial force regions.

FIG. 55 shows a clot retrieval device 3151 comprising a shaft 3152, anouter member 3154 and an inner member 3153. The inner member 3153 has afirst diameter region 3156 connected to shaft 3152 by connecting arms3162, a second diameter region 3157 which is smaller in diameter thanthe first diameter region, a third diameter region 3158 which is largerin diameter than the second diameter region, and a flared out fourthregion 3159 whose maximum diameter is greater than that of any of theother regions. In the embodiment shown a distally inwardly taperingconical or dome shaped region 3160 is connected to flared out region3159, and a flexible tip 3161 is attached to the distal end of region3160. In other embodiments the flared distal region may terminate in anopen end, rather than in a closed end with a tip. This stepped diameterdesign has a number of benefits: 1) the reduced diameter region(s) 3157help grip the clot in which the device is deployed by creating amechanical engagement between device and clot, 2) the reduced diameterregion(s) 3157 may reduce the risk of hemorrhagic conversion byproviding a defined flow lumen which controls the rate of blood flowthrough the device while deployed in clot, thus avoiding the abruptlarge increase in flow and pressure that would be created by a moresignificant displacement or removal of the clot blockage. 3) the reduceddiameter region(s) 3157 provide hinge points to make the device flexibleand atraumatic during delivery and retraction. This stepped and/orflared configuration may be applied to any of the inner tubular membersdisclosed elsewhere in this document.

The flared end 3159 of the inner tubular member 3151 assists incontrolling the position of the inner tubular member relative to theouter member 3154 and avoiding snagging of any terminal end point(s) ofthe inner tubular member within the struts of the outer member. This isof particular benefit if there is a significant change in length (due toforeshortening) of the outer member relative to the inner (or viceversa) between the wrapped delivery configuration and the expandeddeployed configuration. Other means of avoiding snagging and controllingthe position of the inner tubular member distal region are illustratedelsewhere, and include a spring wire connection (as shown in FIG. 51 b),a sliding collar configuration (as shown in FIG. 52 b), a tetheredconnection between a flared end of the inner and the distal end of theouter member (as shown in FIG. 70) and a matched foreshortening of innerand outer members to avoid any relative length change.

Outer member 3154 may terminate in an open ended design at end 3155 asshown, or may comprise a closed or scaffolded distal end as illustratedin FIGS. 51 and 52 and elsewhere in this document.

FIG. 56 a shows a side view of an inner tubular member 3201 deployed ina bend. The inner tubular member 3201 comprises a plurality of struts3202 connected at junction points 3203 and defining cells 3205 such thatfour such cells surround the circumference of the member. Thus whenplaced in a bend cells on the inside of the bend are placed incompression, cells on the outside of the bend are placed in tension, andthe cells on either side of the inner tubular member generally alignedwith its neutral axis are under a significantly lower stress. Thesymmetry of a four cell construction as shown means that the degrees offreedom afforded each of the struts and junction points allows the cellsto deform and the tube to bend to a very tight bend radius withoutkinking. This is illustrated by FIG. 56 b, which shows a section viewthrough the tightest bend radius of device 3201, showing that the outersurface 3221 has maintained a generally circular shape, thus maintaininga large flow lumen 3222 through the inside of the tubular member.

FIG. 57 a illustrates the kinking 3253 that can occur in a conventionalstent-like tube 3251 comprising interconnected struts 3252 configured afive cell or greater design when placed in a tight bend. FIG. 56 b showsa section view through the tightest bend radius of device 3251, showingthat the outer surface 3271 has collapsed into a flattened shape, thusfailing to maintain a sufficient flow lumen 3222 through the inside ofthe tubular member.

FIG. 58 a shows an isometric view of an outer member 3301 of thisinvention. Outer member 3301 comprises three self-expanding segmentsconnected by two rib members. First self expanding segment 3303 isconnected at proximal junction 3306 to elongate member 3302, andcomprises three ring members 3307, 3309 and 3310. Proximal ring member3307 is only connected to member 3301 at proximal junction 3306, and itsdistal crown or apex 3308 is not connected to any adjacent ring member.This means that proximal ring member 3307 can maintain good appositionwith the wall of a vessel in which it is deployed even when the outermember is placed in tension as it might be when being retracted throughtortuousity, which is beneficial in preventing the loss of any clotbeing held by the outer member around or proximal of said ring member.Second ring member 3309 is connected at its proximal end to elongatemember 3302 and proximal ring member 3307 by connecting arm 3317, and atits distal end 3312 to rib member 3313. Third ring member 3310 comprisesapproximately a half circumference of the outer member, and is connectedto second ring member 3309 at junction point 3311. Second self expandingsegment 3304 and third self expanding segment 3305 are of a similarconstruction to first self expanding segment 3303. Second self expandingsegment 3304 is oriented at 180 degrees to the first self expandingsegment 3303, and is connected to it by rib member 3313, while thirdself expanding segment 3305 is oriented at 180 degrees to the secondself expanding segment 3304, and is connected to it by rib member 3314.

The three self expanding segments are separated by inlet mouths 3318 and3319, which allow portions of the clot to enter a reception spacedefined by the outer member and an inner tubular member disposed withinit.

In the embodiment shown the distal crowns 3315 and 3316 comprise thedistal end of the outer member, but in other embodiments a capture netmay be appended to the outer member as disclosed elsewhere in thisdocument, and in yet other embodiments the distal end of the outermember may comprise radially inwardly projecting struts to create a clotretaining scaffolding region which may in some embodiments also comprisescaffolding fibres, as for example illustrated in FIG. 52 b.

FIG. 58 b is a developed view of the outer member 3301 of FIG. 58 a.

FIG. 59 a shows an isometric view of an outer member 3351 of thisinvention. Outer member 3351 comprises three similar self-expandingsegments connected by two pairs of rib members. First self expandingsegment 3356 comprises a first ring member comprised of four struts3353, a second ring member comprised of four struts 3363 and two diamondshaped cells formed by the second ring member and struts 3368. The firstand second ring members contain unconnected terminal crowns 3355 and3354 respectively, and are connected to each other by connecting struts3365. The first self expanding segment 3356 is connected at points 3369to elongate shaft 3352 by two connecting arms 3366. The second selfexpanding segment 3357 is similar to the first one, and is connected toit by parallel rib members 3361, which run between junction points 3364and 3362. The third self expanding segment 3358 is similar to the firstand second ones, and is connected to the second self expanding segmentby parallel rib members 3360, In the embodiment shown the third selfexpanding segment of the outer member comprises terminal crowns 3359,but in other embodiments a capture net may be appended to the outermember as disclosed elsewhere in this document, and in yet otherembodiments the distal end of the outer member may comprise radiallyinwardly projecting struts to create a clot retaining scaffolding regionwhich may in some embodiments also comprise scaffolding fibres, as forexample illustrated in FIG. 52 b.

The three self expanding segments are separated by inlet mouths 3370,which allow portions of the clot to enter a reception space defined bythe outer member and an inner tubular member disposed within it.

In another embodiment of this invention the third self expanding section3358 and ribs 3360 are oriented at 90 degrees to that which is shown inFIG. 59 a, so that the ribs 3360 are connected to the secondself-expanding segment at crowns 3367.

FIG. 59 b is a developed view of the outer member 3351 of FIG. 59 a.

FIG. 60 a is a developed view of another outer member of a clotretrieval device of this invention. Outer member 3401 is aself-expanding component comprised of a proximal scaffolding region3402, a middle scaffolding region 3403 and a distal scaffolding region3404. Inlet mouths 3405 and 3406 lie between the scaffolding sections sothat clot can be urged by the scaffolding sections through the inletmouths into a reception space within the outer member. Each scaffoldingsection comprises a plurality of struts 3407 and crowns 3408, includingin this embodiment unconnected terminal crowns 3409. Each scaffoldingsection is connected to the neighbouring scaffolding section by ribs3410 which in this embodiment contain hinge features 3411. The proximalscaffolding section 3402 is connected to a proximal junction point orcollar 3412 by proximal connecting arms 3413. The distal scaffoldingsection 3404 comprises a plurality of radially inwardly projectingstruts 3415 which in this embodiment terminate a distal junction pointor collar 3414, and comprise multiple fibre connection features 3416,which may be eyelets or other shapes such as shown in FIGS. 24 and 25,Radiopaque markers 3417 may be positioned on the outer member to aid invisualization of the position and condition of the device underfluoroscopy.

FIG. 60 b is a close-up view of an atraumatic feature appended to thedistal end of a distally facing terminal (unconnected) crown of an outermember, such as crown 3409 of FIG. 60 a for example. Atraumatic tipfeature 3432 is a radially inwardly curving tapered strut connected atits proximal end to crown 3431 and terminating in a rounded end 3433.

FIG. 60 c is a close-up view of an atraumatic feature appended to thedistal end of a distally facing terminal (unconnected) crown of an outermember, such as crown 3409 of FIG. 60 a for example. Atraumatic tipfeature 3442 comprises slot features 3444 and is connected at itsproximal end to crown 3441 and terminates in a ball-nose end 3443. Slotfeatures 3444 add flexibility to the tip feature to enable it to deflectat a very low force under a lateral or compressive load such as might beexperienced when contacting a vessel wall.

FIG. 61 shows a clot retrieval device 3451 of this invention comprisingan inner tubular member 3453 and an outer member 3457. Outer member 3457comprising a plurality of ring elements 3454 connected at their proximalends to axial rib 3455, which is in turn connected at its proximal endto elongate shaft 3452. A distal capture net 3456 is connected to thedistal most ring of ring members 3454.

FIG. 62 shows another outer member of a clot retrieval device of thisinvention, in which three saddle shaped members 3502, 3503 and 3504 areconnected to each other by connector arms 3506 and 3507 and to aproximal connection point 3501 by connector arms 3505. Such an outermember may be used in conjunction with any of the inner tubular membersdisclosed elsewhere in this document, and may be used in conjunctionwith any of the capture net designs disclosed elsewhere in thisdocument, which may be separate to the outer member such as illustratedin FIG. 1 a or integral to the outer member such as illustrated in FIG.52 b.

FIG. 63 a and FIG. 63 b show an isometric view and a side viewrespectively of an outer member 3551 of an engaging basket of a clotretrieval device of this invention. Outer member 3551 comprises aplurality of struts connected is such a way as to create two parallelrib members comprising a series of connected diamond shaped cells 3554composed of strut members 3555, and a plurality of V shaped memberscomposed of pairs of struts 3556, which are connected at their proximalends to diamond cells 3555 and at their distal ends to spring elements3557. The rib members are connected to a proximal collar or connectionpoint 3552 by connecting arms 3553. This outer member thereforecomprises two basic cell types: diamond cells 3555 and five sided cells3559. The purpose of the ribs of diamond cells 3555 is to act as forcetransmitters through the device so that when paced in tension (as whenretracting captured clot through tortuosity) this tensile force istransmitted through the diamond cells 3555 and connector arms 3553 toproximal collar 3552, rather than through five sided cells 3559. Thisallows the device to maintain its diameter and hence avoid loss ofcaptured clot. Spring element 3557 is able to stretch to shape 3557 a orcompress to shape 3557 b at very low forces so that the device maintainits shape and avoid kinking in bends, Such a construction has thebenefit of preventing the migration of any of the crowns 3560 of thedevice from migrating into and damaging the small and delicateperforator vessels that branch from the walls of the cerebral arteries.Such an outer member may be used in conjunction with any of the innertubular members disclosed elsewhere in this document, and may be used inconjunction with any of the capture net designs disclosed elsewhere inthis document, which may be separate to the outer member such asillustrated in FIG. 1 a or integral to the outer member such asillustrated in FIG. 52 b.

FIG. 64 a shows a side view of another outer member 3601 of an engagingbasket of a clot retrieval device of this invention. Outer member 3601is identical to member 3551 of FIG. 63 a except that a number of strutshave been removed from the diamond cell ribs (such as between points3602 and 3603) to create large inlet openings 3604, into which clot mayflow. Such an outer member may be used in conjunction with any of theinner tubular members disclosed elsewhere in this document, and may beused in conjunction with any of the capture net designs disclosedelsewhere in this document, which may be separate to the outer membersuch as illustrated in FIG. 1 a or integral to the outer member such asillustrated in FIG. 52 b.

FIG. 64 b shows a side view of another outer member 3651 of an engagingbasket of a clot retrieval device of this invention. Outer member 3651is identical to member 3551 of FIG. 63 a except that a number of strutshave been removed from the diamond cell ribs (such as between points3652 and 3653) and from the five sided cells (such as between points3654 and 3655) to create large inlet openings 3656, into which clot mayflow. Such an outer member may be used in conjunction with any of theinner tubular members disclosed elsewhere in this document, and may beused in conjunction with any of the capture net designs disclosedelsewhere in this document, which may be separate to the outer membersuch as illustrated in FIG. 1 a or integral to the outer member such asillustrated in FIG. 52 b.

FIG. 65 a shows a side view of another outer member 3671 of an engagingbasket of a clot retrieval device of this invention. Outer member 3671is similar to member 3551 of FIG. 63 a except that four of struts 3557have been removed to create four large inlet openings 3677, into whichclot may flow. Removing these struts creates three segments: proximalsegment 3672 is connected to middle segment 3673 at hinge points 3678,and middle segment 3673 is connected to distal segment 3674 at hingepoints 3679, The distal segment comprises a dome shaped scaffoldingsection 3675 to which is appended a distal flexible tip 3676. Such anouter member may be used in conjunction with any of the inner tubularmembers disclosed elsewhere in this document, and may be used inconjunction with any of the capture net designs disclosed elsewhere inthis document, which may be separate to the outer member such asillustrated in FIG. 1 a or integral to the outer member as shown in thisembodiment. This segmented design allows the device to interact with andgrip clot and maintain excellent wall apposition in bends and in tensionin a similar manner to that described in FIGS. 14 a-d and also in FIGS.83 a-b.

FIG. 65 b shows a top view of a mid portion of another outer member 3685of an engaging basket of a clot retrieval device of this invention. Thisview shows one embodiment of the mid section 3673 of the device 3671 inFIG. 65 a. This mid section has a similar construction to that of 3673(which is similar to that of 3551 shown in FIG. 63 a), but differs inthat it has additional terminal crowns 3689 and a shorter axial strut3686. The terminal crowns 3689 are created by the junction of the distalends of struts 3687 and 3688. This design creates a six sidedscaffolding cell 3690, whose terminal crown 3689 is spaced apart fromthat of adjacent cell 3691. This effectively creates an additionalterminal crown, whose apex provides a “saddle point” which can assist inthe gripping and dislodgement of clot.

FIG. 66 is side view of the scaffolded distal end of an outer member3701 of this invention, and shows an atraumatic scaffolding design thatcould be applied to many of the elsewhere disclosed outer members.Struts 3702 terminate in crowns 3703, to which are attached radiallyinwardly projecting hoop elements 3704, which are interconnected througheyelets 3705 at their distal end by tether element 3706. By not rigidlyconnecting eyelets 3705, the hoop elements 3704 are free to deflect at avery low force in response to a compressive force such as contact with avessel wall. At the same time hoops 3704 and tether 3706 provide a highdegree of scaffolding to prevent the distal migration of clot heldwithin the outer member.

FIG. 67 is an isometric view of the scaffolded distal end of an outermember 3751 of this invention, and shows an atraumatic scaffoldingdesign that could be applied to many of the elsewhere disclosed outermembers. In this design a compliant section has been added to theinwardly facing distal struts of the device so that it can deflect at avery low force when compressed. This approach can be used in conjunctionwith fibres as shown elsewhere to provide a highly atraumatic and wellscaffolded capture net. Connection points 3752 represent the points ofattachment of structure 3751 to the distal section of an outer member,or could be a part of the outer member itself in an embodiment wherestructure 3751 is integral to the outer member. Inwardly projectingtapered struts 3753 run between connection points 3752 and compressiblestruts 3755, which are in turn connected to distal collar 3756.Compressible struts 37555 comprise compliant sections 3757 whichconsists of undulating regions with a plurality of inflection points3758.

FIG. 68 is an isometric view of the distal end of an outer member 3801of this invention, and shows an atraumatic strut design that could beapplied to many of the elsewhere disclosed outer members. Outer member3801 comprises a plurality of struts 3802 of wall thickness 3805 in afirst region proximal of its distal end, and a plurality of struts 3804of wall thickness 3806 in a second region adjacent its distal end anddistal of the first region, and a plurality of struts 3803 in a thirdregion lying between the first and second regions whose wall thicknesstapers from a dimension equal to or less than 3805 to a dimension equalto or greater than 3806. In the embodiment shown struts 3804 terminatein distal collar 3807, while in other embodiments the distal ends ofstruts 3804 may be free floating or interconnected without a collar ortethered or connected to an inner tubular member. An advantage of thisdesign is that the distal end of the outer member can be made veryflexible and atraumatic by thus reducing the strut wall thickness. Thestrut width can also be reduced by machining a narrower strut, so thatthe resultant second moment of area of the distal struts 3804 issignificantly lower than that of struts 3802. Thus struts 3802 canprovide a high radial force to grip clot, while struts 3803 and 3804 canprovide effective clot scaffolding and a smooth stiffness transition toa soft distal end. Achieving a smooth stiffness transition in thismanner is very advantageous for deliverability, particularly whenadvancing such a device through a small diameter microcatheter aroundtortuous bends.

Achieving the desirable tapered strut wall thickness described above isnot easy using conventional methods for stent or stent-like clotretriever manufacture such as laser machining, because the cutting tool(in this case a laser) is typically working at right angles to thesurface of the tube or sheet from which the device is being cut.Therefore varying the strut width can easily be achieved but varying thestrut thickness cannot.

One method of achieving the desirable tapered strut wall thicknessdescribed above is to taper the wall thickness of the tubing (or sheet)from which the component is cut. FIG. 69 shows a cross-section through atube 3851 which has a lesser wall thickness 3853 at its distal end thanthe wall thickness 3852 at its proximal end. This difference in wallthickness could be achieved by grinding, etching, polishing or otherwiseremoving material from the outer or inner diameter of the tube, Thisdifference in wall thickness could also be achieved by grinding,etching, polishing or otherwise removing material from the outer orinner diameter of the fully or partially machined outer member, eitherbefore or after expansion to its nominal size and polishing.

In another embodiment of outer member 3801 the thin wall distal sectioncomprising struts 3804 could be machined from a different tube or sheetthan that from which struts 3802 were machined, and the two componentssubsequently assembled together by welding or bonding or tethering.

Yet another method of achieving the desirable tapered strut wallthickness described above is to offset the cutting tool (which may forexample be a laser beam) from the central axis of the tube. This methodis described in more detail in relation to FIGS. 92 to 94.

FIG. 70 a shows a side view of the distal end of a clot retrieval deviceof this invention, comprising an inner tubular member 3902 and an outermember 3903. Inner tubular member 3902 comprises a plurality of struts3907 and terminates in a distal tip 3906 which is connected to the bodyof the inner tubular member by distal arms 3909. The distal region ofthe inner tubular member also comprises a plurality of outwardlyprojecting scaffolding struts 3912 terminating in eyelets 3905. Thedistal region of outer member 3903 comprises a plurality of struts 3911containing eyelets 3904, and a plurality of inwardly projectingscaffolding arms 3910 also comprising eyelets at their terminal ends.The outwardly projecting struts 3912 of the inner tubular member areconnected to the inwardly projecting struts 3910 of the outer member byone or more fibres 3908 passing through eyelets 3905 and 3904. Thus thefibre(s) 3908 in conjunction with the struts of the inner and outermembers form a scaffolding web at the distal end of the outer member asshown in FIG. 70 b, which is an end view of the device of FIG. 70 a.

FIG. 71 shows an isometric view of the distal end of an outer member ofa clot retrieval device of this invention. The distal region of outermember 3951 comprises a plurality of struts 3952 containing eyelets 3953through which are threaded one or more fibres 3954 such that thefibre(s) form a scaffolding web at the distal end of the outer member.

FIG. 72 shows a side view of the distal end of a clot retrieval device4001 of this invention, comprising an inner tubular member 4002 and anouter member 4003. The distal region of outer member 4003 comprises aplurality of struts 4004 containing eyelets 4005. A plurality of fibres(or a single fibre folded back on itself multiple times) 4006 arethreaded through eyelets 4005 and connected to the distal end of theinner tubular member 4002 at collar 4007, such that an inverted net 4008is formed, where the distal most end of the net comprises a highlyatraumatic brush of fine diameter fibres. This construction has theadded advantage of providing a compliant connection between the end ofthe inner tubular member 4002 and the outer member 4003, which canaccommodate some length change during loading and deployment andminimises the risk of snagging of one element in the other. In anotherembodiment the fibres are further configured in a knitted or braidedpattern.

FIG. 73 shows an isometric view of the distal end of an outer member ofanother clot retrieval device of this invention, somewhat similar tothat illustrated in FIG. 52 b. The distal region of outer member 4051comprises a plurality of struts 4052 defining a generally cylindricalshape, from which a plurality of struts 4053 project radially inward tojunction point 4054, to which a radiopaque and flexible distal tip 4055is attached. Fibre 4056, which may be one continuous fibre or multiplefibres, is threaded through eyelets 4052 around the outer member suchthat a scaffolding web is formed at the distal end of the outer member.

FIG. 74 a shows a side view of a clot retrieval device of thisinvention, comprising an inner tubular member 4102 and an outer member4103 connected at their proximal ends to an elongate shaft 4114. Outermember 4103 comprises a self-expanding generally cylindrical proximalsection 4104 and a self-expanding distal section 4105 comprising agenerally conical or dome shaped distal, end to which is appended aflexible tip 4108. The proximal and distal sections of the outer memberare connected by two connecting arms 4106 and 4107, which adopt agenerally spiral configuration as shown in the unrestrained expandedstate. The distal ends of the inner and outer members are connected byan axially compliant spring section 4109, which can accommodate a changein length and/or rotational movement between the inner and outer membersduring use. In other embodiments the distal ends of the inner and outermembers may not be connected, or may be constrained without a fixedconnection. Inner tubular member 4102 comprises a plurality of zones ofdiffering radial force and flexibility, which may be created bydiffering strut geometries and configurations as described in relationto FIG. 54. A high radial force zone 4110 is located at the proximal endof the inner tubular member, and sits proximal of the scaffoldedproximal section 4104 of the outer member, so that when deployed withina clot this zone of the inner tubular member can expand and grip theclot and create a flow lumen through that portion of the clot. Arelatively lower radial force zone 4111 is located distal to zone 4110,and sits beneath the scaffolded proximal section 4104 of the outermember, so that when deployed within a clot the combined radial force ofthe inner and outer members is sufficient to grip the clot and create aflow lumen through that portion of the clot, while the longer, thinnerstruts of this zone provide this portion of the inner tubular memberwith greater bend flexibility than its neighbouring high radial forcezone. A high radial force zone 4112 is located at the proximal end ofthe inner tubular member, and sits between the scaffolded proximalsection 4104 and distal section 4105 of the outer member, so that whendeployed within a clot this zone of the inner tubular member can expandand grip the clot and create a flow lumen through that portion of theclot. A relatively lower radial force zone 4113 is located at the distalend of the inner tubular member, and sits beneath the scaffolded distalsection 4105 of the outer member, so that when deployed within a clotthe combined radial force of the inner and outer members is sufficientto grip the clot and create a flow lumen through that portion of theclot, while the longer, thinner struts of this zone provide this portionof the inner tubular member with greater bend flexibility than itsneighbouring high radial force zone.

FIG. 74 b shows a side view of the device 4101 of FIG. 74 a in acollapsed configuration as it might be for delivery through amicrocatheter. During loading into a small diameter tube the twoconnecting arms 4106 and 4107 extend and straighten to adopt a positiongenerally parallel to the axis of the device. As a consequence of thisthe distal section 4105 of the outer member tends to rotate relative tothe proximal section 4104 once the device is deployed and allowed toexpand. This rotating action and reduction in distance between proximaland distal outer member sections serves to trap clot beneath theconnecting arms and within the reception space between inner and outermembers.

FIG. 75 shows a graph 4151 plotting radial pressure on the vertical axis4153 and vessel diameter on the horizontal axis 4152. The bars on thegraph depict the radial pressure of different devices or devicecomponents at different vessel diameters. Point 4155 on the horizontalaxis represents the smallest vessel diameter in which these clotretrieval devices are intended to be used, which might for example be1.5 mm. Point 4156 represents a typical diameter of a vessel throughwhich these clot retrieval devices are expected to be deployed andwithdrawn, for example 3.0 mm. Point 4154 represents a diameter to whichit is desirable that the device expand to within the target clot tocreate a flow lumen and to grip the clot, said diameter being less thanthe smallest vessel diameter in which these clot retrieval devices areintended to be used, for example 1.0 mm. Two radial pressure levels aremarked on the horizontal axis: it is desirable that devices exert aradial pressure on the vessel of less than the level represented by line4163 in order to avoid vessel trauma, and it is desirable that devicesexert a radial pressure on the clot of more than the level representedby line 4164 in order to create a lumen through the clot and hencerestore blood flow to the ischaemic brain tissue and reduce the pressuregradient across the clot. It is very difficult for a singleself-expanding component such as the typical stent-like clot retriever201 illustrated in FIG. 13 to meet these two contradicting radialpressure desires, and hence typical stent-like clot retrievers tend tohave an intermediate radial strength that is not high enough toguarantee a flow lumen through the clot yet is not low enough toguarantee avoidance of vessel trauma. This undesirable trade-off isovercome by the dual layer clot retrieval devices of this invention,because the inner tubular member can be configured to deliver a strongradial pressure but have a maximum expanded diameter of less than thesmallest vessel diameter in which these clot retrieval devices areintended to be used, and the outer member can be configured to deliver alower radial pressure than would be traumatic to the vessel.

These radial pressure levels are illustrated by the bars of graph 4151:

Bar 4157 shows the radial pressure of a typical stent-like clotretriever when expanded to a low diameter 4154, and bar 4160 shows theradial pressure of a typical stent-like clot retriever when expanded toa higher diameter 4156, showing that the radial force exerted atdiameter 4154 may not be sufficient to open a flow lumen, and the radialforce exerted at diameter 4156 may be too high to guarantee anatraumatic vessel contact.

Bar 4158 shows the radial pressure of an inner tubular member of thisinvention when expanded to a low diameter 4154, and bar 4161 indicatesthat the inner tubular member exerts zero radial pressure on the vesselat vessel diameter 4156 because the vessel diameter is larger than thediameter of the inner tubular member. Thus it can be seen that the innertubular member alone has the radial strength to expand to diameter 4154and create a flow lumen through the clot, but does not exert any radialpressure on the vessel because its maximum expanded diameter is lessthan that of any vessel in which it is deployed.

Bar 4159 shows the radial pressure of an outer member of this inventionwhen expanded to a low diameter 4154, and bar 4162 shows the radialpressure of the outer member when expanded to a higher diameter 4156.However the effective radial pressure exerted by the clot retrievaldevice is actually the sum of that exerted by the inner tubular memberand that exerted by the outer member. Thus the radial force seen by theclot is high, and that seen by the vessel is low. The design of theouter member may have one or more of a number of features such as inletmouths, articulation regions, ribs and clot grip features (all disclosedin this document) that enable it to retain a secure grip on the clot ata low radial force.

Thus with a dual layer design of inner and outer tubes it is possible toprecisely create the desired ratio of the radial pressure (or outwardradial force per unit area) exerted by the device at diameter A to theradial pressure exerted by the device at diameter B, where diameter A isa diameter smaller than that of the vessel in which the target clot islodged, and diameter B is a diameter greater than that of the vessel inwhich the target clot is lodged. For example in the case of aneurovascular clot retrieval device it may be desirable to have a devicethat can be deployed in cerebral arteries down as small as 1.5 mmdiameter. In this case it would be desirable to exert a strong clotopening radial pressure up to 1.5 mm and then exert a much lower clotretaining radial pressure at and above 1.5 mm. Therefore it would bedesirable that the radial pressure ratio between a 1 mm diameter and 2mm diameter be at least 2:1, and more preferably at least 2.5:1 and mostpreferably greater than 3:1. In another embodiment of a clot retrievaldevice tailored for a larger target vessel it would be desirable thatthe above pressure ratios be achieved between a 2 mm diameter and a 3 mmdiameter. In another embodiment of a clot retrieval device tailored foran even larger target vessel it would be desirable that the abovepressure ratios be achieved between a 3 mm diameter and a 4 mm diameter.In another embodiment of a clot retrieval device tailored for a stilllarger target vessel it would be desirable that the above pressureratios be achieved between a 4 mm diameter and a 5 mm diameter.

In one embodiment the radial force exerted by the clot retrieval deviceis relatively constant over the length of the clot engaging portion. Inanother embodiment the radial force exerted by the clot retrieval devicechanges significantly over the length of the clot engaging portion. Thescaffolding and inlet mouth sections of many of the outer membersdisclosed in this document create a stepped radial force profile alongthe device length, which is beneficial in clot gripping and in urgingclot to move from a high radial force area to lower radial force (inletmouth) area.

FIGS. 76 a-c show side views of one embodiment of a clot retrievaldevice of this invention being used to retrieve a clot 4202 from avessel 4201. The clot retrieval device comprises an elongate shaft 4207,an outer member 4204, an inner tubular member 4203 and a capture net4205. The outer and inner members are connected at their proximal endsto the distal region of the elongate shaft, and the capture net isconnected by connecting arms 4210 to the distal end of the inner tubularmember.

The device is shown upon initial deployment in the target clot in asmall diameter vessel in FIG. 76 a. FIG. 76 b shows the device withdrawna short distance from its initial deployment position, so that it issituated in a slightly larger diameter vessel and has thus expandedsomewhat in diameter. FIG. 76 c shows the device retracted a significantdistance from its initial deployment position so that it is situated ina significantly larger diameter vessel (close to a side branch 4208) andhas thus expanded significantly in diameter.

The outer member shortens in length as it expands so that the distancebetween the distal end 4206 of the outer member and the mouth 4209 ofthe capture net increases as the device expands, which means that thisdistance increases as the device is retracted into larger more proximalvessels than that it which it was initially deployed. Increasing thedistance between the distal end 4206 of the outer member and the mouth4209 of the capture net means that a larger opening is created betweenthe two as shown in FIG. 76 c, so that it is easier for any clotfragments that may be liberated during retraction, such as when passinga side branch 4208 for example, or when being retracted into a receivingcatheter (not shown), to enter the mouth of the capture net.

The degree to which the distance between the distal end 4206 of theouter member and the mouth 4209 of the capture net increases uponexpansion depends on the relative foreshortening of the inner and outermembers. This foreshortening is design dependent it can be minimized oralmost completely eliminated by the use of backbones such as elements773 illustrated in FIG. 33, or it can be increased by increasing theexpanded opening of designs with cell structures (for example angle 1472of FIG. 48 d). In this way the outer member may be configured with largeopening angles so that it foreshortens significantly upon expansion, andthe inner tube to which the capture net is connected could be configuredwith a backbone design such as is shown for the outer member of FIG. 33so that it has minimal foreshortening upon expansion.

FIGS. 77 a-b show side views of another clot retrieval device 4251 ofthis invention in action retrieving a clot 4257. Device 4251 comprisesan outer member 4254 similar to member 2029 of FIG. 51 a, an innertubular member 4258 and an elongate shaft 4252. Inner tubular member4258 is connected to the end of elongate shaft 4252, and sits withinouter member 4254, which is itself slidably connected to elongate shaft4252 by collar 4259 which can travel between shaft stop 4253 and theproximal end of the inner tubular member, with spring element 4260sitting over the shaft between collar 4259 and the proximal end of theinner tubular member. The outer member 4254 comprises a proximalscaffolding section 4255 and a distal scaffolding section 4256, spacedapart by clot inlet mouths 4261. Thus the outer member 4254 can movedistally relative to the inner tubular member during retrieval, so thatthe proximal self-expanding section 4255 of the outer member can slideover clot 4257 which is held by inner tubular member 4258 and trap theclot between itself and the inner tubular member as shown in FIG. 77 b.

In another embodiment of this invention a shorter inner tubular isemployed, so that the distal end of the inner tubular member sitsadjacent the distal end of the proximal scaffolding section 4255 of theouter member in the retracted configuration illustrated in FIG. 77 b. Inthis way a larger reception space is created under inlet mouth 4261 sothat clot can be more readily accepted into the interior of the device.

In yet another embodiment of this invention the movement of the deviceis reversed, so that the outer member slides proximally upon retraction,which assists the distal scaffolding section 4256 of the outer member insliding over the clot and trapping it.

FIGS. 78 a-b show side views of another clot retrieval device 4301 ofthis invention in action retrieving a clot 4308. Device 4301 comprisesthree clot engaging segments connected to an elongate shaft 4309.Proximal clot engaging segment 4302 and distal clot engaging segment4304 are connected to shaft 4309 at collars 4305 and 4307 respectively.Middle clot engaging segment 4303 is connected at its proximal end tocollar 4306 which is slidable on shaft 4309 between collars 4305 and4307. FIG. 78 a shows the device 4301 as it might look when initiallydeployed within a vessel under clot 4308. As the device is retractedproximally the friction between the middle segment 4303 and the vesselwall urges the middle segment distally relative to the shaft andproximal and distal segments, pinning clot 4308 between the middle anddistal segments. This pinning mechanism provides a secure grip on theclot for safe retraction through the vasculature and out of the patient.

FIGS. 79 a-d illustrate a method of use of clot retrieval device 2101(FIG. 52 a) of this invention, and is also illustrative of the method ofuse of many of the other clot retrieval devices disclosed herein.

FIG. 79 a shows a vessel 4351 in which is lodged a clot 4353. Amicrocatheter 4352 is shown having crossed the clot, which may have beenachieved with the aid of a guidewire (not shown).

The lumen of the microcatheter can now be used as a tunnel through whichto advance the clot retrieval device until the tip of the clot retrievaldevice reaches the distal end of the microcatheter. The microcathetercan then be retracted to leave the clot retrieval device deployed acrossthe clot as shown in FIG. 79 b. At this point the inner tubular member2117 is fully or almost fully expanded to a diameter less than that ofthe vessel segment in which it is deployed, but sufficient to provide ablood flow pathway through the clot to the distal vascular bed. Theouter member 2112 is partially expanded and its expanding scaffoldingsections 2104 and 2105 have urged the clot at least partially throughinlet mouths 2120 and 2121, so that the clot is securely held without ahigh radial pressure being exerted on the vessel. Holding the clotwithout excessively deforming it enables the clot to be retracted in onepiece from a bifurcation as shown.

FIG. 79 c shows the device 2101 retracting the captured clot 4353 into amore proximal segment of vessel 4351, showing clot fragments 4357trapped in scaffolded distal cone 2123.

FIG. 79 d shows the device 2101 being withdrawn into the distal tip of aguide catheter 4358, showing clot fragments 4357 trapped in scaffoldeddistal cone 2123.

FIG. 80 shows the distal end of clot retrieval device 4401 deployed invessel 4403. A soft “pig tail” tip 4402 is attached to the distal end ofthe clot retrieval device 4401 with a pre-formed curl to minimize therisk of the distal end 4405 of the tip entering into any small sidebranches such as perforator vessel 4404 shown, where it might causeinjury to the vessel wall. This type of atraumatic tip feature isparticularly important for clot retrieval devices which are deliveredthrough catheters to the target site, as there is a risk that they maybe unintentionally advanced (particularly during deployment) within thedelicate vessels of the brain. Many of these vessels have smallervessels such as perforators or lenticulostriates branching from theirwalls, and these vessels may be easily harmed if an element of the clotretrieval device snags within them and is advanced. One method ofavoiding such a snag is to minimize the risk of an element of the deviceentering such a small side branch vessel in the first place, and the“pig tail” tip is one way of doing this. Another is to employ a domeshaped end for the distal surface of the outer member, such as in FIG.51, 60, 61, 66, 67, 72, so that the convex curvature of the outer memberdistal end keeps any protuberance at its distal apex (if present) awayfrom the wall of the vessel. Yet another approach is to ensure that thedistal end of the device is soft and deformable in compression, such ashas been described in various other parts of this document including inFIGS. 66-68, and in FIGS. 81 and 82 below.

FIG. 81 shows a partially sectioned side view of the distal end of aclot retrieval device 4451 comprising a distal arm 4452 which tapers toa smaller cross-sectional area in its distal region 4453 than at itsproximal end. A spiral coiled element 4455 is positioned over the arm4452 and joined to it at its distal tip by joining material 4456. In oneembodiment this coiled element is a radiopaque metallic wire such asplatinum or gold or an alloy of same, and the joining material is asolder such as silver or an alloy of same. In other embodimentsalternative coil materials may be employed and alternative joiningmaterials and methods such as brazing, adhesive bonding or welding maybe used. A space is left between some or all of the coils of the spiralcoiled element 4455 as shown so that it can be deformed and bend orcompress at a very low force. The distal arm 4452 comprises a curvedshape in its relaxed state so that it is effectively pre-set with apreferred buckle point, and will thus deflect a low force by bending ifa compressive load is applied to it. In another embodiment a ductilecore wire is provided inside the tip so that the tip can be formed intoa preferred shape by a user prior to use.

FIG. 82 shows a side view of the distal end of a clot retrieval device4501 in which a soft and deformable distal tip has been machined fromthe same tubing from which the body of the clot retrieval device hasbeen machined. This design has the advantage of not requiring anyadditional joining materials which might add stiff regions to the tip aswell as adding to the device length, complexity and cost. Clot retrievaldevice 4501 comprises a distal collar 4502 and an integral distal tip4506 which has been machined to render it highly flexible in bending byremoving slots of material in region 4503, and by means of a spiral cutwith connecting bridges in region 4504, and by means of a spiral cutwithout connecting bridges in region 4507. A round ball end 4505 isprovided at the distal end to create a smooth and atraumatic distalsurface. A preset curve may be added to the tip as shown to ensure thatit bends in response to a compressive load, rather than initiallybuckling as might be the case with a perfectly straight tip. In anotherembodiment a ductile core wire is provided inside the tip so that thetip can be formed into a preferred shape by a user prior to use.

FIGS. 83 a and 83 b show a schematic drawing of an engaging basket clotretrieval device 4603 deployed in a clot 4604 in a vessel 4601 withcentre-line 4602. These drawings illustrate the nature of theinteraction between engaging baskets or stent-baskets or outer membersof the clot retrieval devices of this invention and the clot which theyare intended to capture and remove. The inventors have discovered thatocclusive clots are highly mobile three dimensional bodies in vivo andthat under the influence of an applied force the clot will change shape,deform and/or migrate (without significant volume change) in preferenceto dehydrating under the influence of the applied force. The energyrequired to dehydrate the clot is in many situations greater than theenergy required to change the shape of the clot. This discovery hasallowed the inventors to define a series of new strategies for capturingand removing occlusive clots in human vessels.

It will be appreciated that an expandable tubular device with sufficientradial force (like a stent) which moves from a small diameter collapsedstate to a larger diameter expanded state while positioned across asubstantial portion or all of a clot length will cause compression anddehydration of the clot.

The current stent-basket invention however discloses a device with aporous expandable tubular element whereby the expandable tubular elementcomprises an outer wall which comprises a plurality of scaffold regionsthat are configured to scaffold clot against the vessel wall as theexpandable tubular element expands outwardly, and a plurality of inletopenings that are configured to allow the clot to migrate through theninto a reception space within the device.

FIG. 83 a shows such a device 4603 immediately after deployment withinclot 4604—before it has had a chance to exert any radial force upon theclot. FIG. 83 b shows the same device 4603 a short period later—when ithas expanded and interacted with the clot. Device 4603 comprisesscaffolding regions 4607, 4608 and 4609, spaced apart by inlet openings4610 and 4611. Clot 4604 in FIG. 83 a is shown comprising multiple zonesfor the purposes of illustrating the effect of the expansion of thedevice within the clot. Zones 4605 of the clot are situated abovestent-basket scaffolding regions and are denoted by multiple whitecircles, while zones 4606 of the clot are situated above stent-basketinlet opening and are denoted by multiple dark circles.

FIG. 83 b shows the device 4603 a certain period post deployment in clot4604—after it has expanded and interacted with the clot. The outwardradial force of the device 4603 has enabled scaffolding sections 4607,4608 and 4609 to expand radially outward, compressing clot zones 4605,but applying minimal compression to clot positioned above the inletopenings 4610 and 4611 in zones 4606. Thus a certain portion of the clotin zone 4605 has been compressed above the scaffolding section asillustrated by oval shapes 4651, and a certain portion of the clotoriginally in zone 4605 has been urged by the compressive force towardsthe unscaffolded inlet openings as illustrated by white circles 4652.Those portions of the clot in zones 4606 originally situated above aninlet opening have been urged through the openings into a receptionspace 4656 as illustrated by dark circles 4653 in zones 4654.

In another embodiment the scaffold regions are connected to form acontinuous scaffold surface. The expandable tubular element comprisesinlet openings in the wall and these inlet openings comprise regionswith substantially no scaffolding. The inlet openings may beinterspersed between scaffold regions or the inlet openings may besubstantially surrounded by a continuous plurality of scaffold regions.

The scaffold regions are configured so as to provide sufficientscaffolding and radial force so as to compress a constrained clot duringexpansion from a collapsed delivery state to at least a partiallyexpanded state. The inlet openings on the other hand are configured suchthey have little or no scaffolding over the inlet area so that clotdirectly over the inlet opening and clot from the adjacent scaffoldregion can flow, deform or migrate through the inlet opening. Theability of the invention to urge clot from the scaffold region to flow,deform or migrate through the inlet opening greatly reduces the volumeof clot in the scaffold region and this has the effect of greatlyreducing the degree to which the clot is compressed.

Preferably the device is configured such that during expansion of thestent-basket the energy required to cause at least some of the clot thatis radially outward of a scaffolding region to flow, deform or migratetowards or through an adjacent inlet is less than the energy needed tocompress (and dehydrate) the clot to a significant degree.

Preferably the device is configured such that during the expansion ofthe device in an occlusive clot that at least some of the clotsandwiched between a scaffold region and the vessel wall is urgedtowards or into an adjacent inlet opening.

Preferably the stent-basket device is configured such that during theexpansion of the device in an occlusive clot that substantially all ofthe clot that is at the inlet opening will pass through the inletopening as the expandable stent-basket expands.

Preferably the relative size and area of the scaffolding regions and theinlet openings is such that the stent-basket can expand to a fullyexpanded diameter that is between 2 times and 18 times that of thecollapsed diameter of the stent-basket.

Strut Holes and Profiles:

Endovascular clot retrieval devices generally have a collapsedconfiguration for device delivery and are deployed and expanded in avessel lumen as part of the treatment procedure. Indeed this alsoapplies to but is not limited to many endovascular devices such asstents, embolic filters, stent grafts, mechanical heart valves, and venacava filters. In order to facilitate device collapse into a deliveryconfiguration, many devices comprise an arrangement of strut featuresconfigured to collapse and expand to facilitate delivery and deploymentrespectively. A common strategy employed in the industry to constructthese devices involves using a laser to cut a pattern from a singlepiece of material such as a tube, expanding and shape setting the cutstructure, and electropolishing it to obtain a smooth surface finish. Aconventional laser cutting process used to cut a pattern through thewall of a tube is described in FIGS. 84, 85 a, 85 b. The strut-basedstructure produced from this process is illustrated in FIG. 86 prior toshape-setting and FIG. 87 shows the structure after it is expanded andshape-set. In the conventional method described in FIGS. 84-87 forreference, the laser source is substantially directly above the centralaxis of the tube. During processing the tube generally rotates about itscentral axis and is translated along its length to cut the desiredpattern into the tube. Intricate features such as small eyelets orlocalised strut narrowing can be machined using the conventional processdescribed in FIGS. 84-87. In the case of clot retrieval devices, eyeletsin the struts may be used attaching fibres to the structure, andnarrowing of the struts allows the structural stiffness to be tailoredto suitable levels along the device length. While these intricatefeatures enhance device performance, features are generally limited tothose in a substantially radial direction.

FIG. 88 shows a novel method of including intricate features in anon-radial direction. Here, a clot retrieval device with existing cutsin a radial direction is translated in the transverse direction and anew intricate feature is cut through the side wall of a strut. Thisfacilitates intricate features such as eyelets through the side wall ofthe struts as shown the expanded device in FIG. 89 a. Side-wall eyeletsare illustratively compared to conventional eyelets for fibre attachmentin FIGS. 90 a, 90 b, 91 a, and 91 b, and the resulting improvement indevice performance is described below.

Minimizing device loaded profile is important in endovascular devicedesign, as reduced profile is generally associated with easier devicedelivery, crossing into the treatment site, and reduced lateral forceson the vessel. The profile is generally determined by the volume ofmaterial in the device, how efficiently it can be wrapped into acatheter lumen space, and the radial reaction force in the wrappedconfiguration at a given lumen diameter. The correct balance of loadedprofile and radial reaction force enables device movement relative to acatheter lumen at an axial force that makes it usable for a physician ina clinical setting. Net fibre attachment to conventional eyelets in clotretrieval devices result in fibre protrusion in a direction normal tothe surface of the device. In conventional eyelets, the fibre runs fromthe inside of the device to its outside, meaning that part of the fibreis located outside perimeter defined by the strut outer circumferenceand thereby increasing the profile, as shown in FIG. 90 b. In contrast,side-wall eyelets allow the entire fibre or net to be located inside thedevice outer perimeter. The side-eyelet shown in FIG. 91 b illustratesthis point, where the fibre starts and ends below the outer surface ofthe device.

Endovascular devices such as clot retrieval devices have key performancecharacteristics, e.g., radial outward force, loading force, deviceflexibility in bends, device kink resistance, which are directlyimpacted by strut width and thickness. The shape and stiffness ofindividual struts and directly contribute to these characteristics, andis therefore a key consideration in device design. Traditionalprocessing techniques for a given pattern limit geometric variations tostrut width, which limits on how flexible individual struts or portionsthereof may be varied for a given tube wall thickness without usingother processing techniques such as grinding or selective etching orelectropolishing. The method disclosed here has the advantage offacilitating strut thickness at very discrete strut sections to optimisedevice radial strength, loading force, flexibility, kink resistance, orany other of the characteristics which are impacted by strut dimensionsthat ultimately lead to improved device performance. Selective strutthinning examples are shown in FIGS. 92 a, 92 b, 93 a, 93 b, and 94.

Strut feature designs variations using this method are also described,for example it is possible to cut an eyelet which enters the outsidewall of the device and exits through the side of a strut, in which casethe fibre entry or exit angle is close to tangential to the surface ofthe device, which has the benefit of preventing kinks or reducing fibrestresses. Simultaneous multiple strut cutting is also possible usingthis technique for processing efficiency, as shown in FIG. 95.Combination eyelets, which have openings in both the normal directionand side-wall is also possible, as shown in FIG. 97. Independentattachment of two or more fibres to a single strut is possible withcombination eyelets.

A clot retrieval device is used by way of example to highlight theadvantages of this disclosure. The benefits of the disclosure extend tominimally invasive structures such as stents, embolic filters, stentgrafts, mechanical heart valves, and vena cava filters, and inparticular to any medical device that comprises a primary supportstructure and a second functional component. By way of example, suchdevices could include a stent graft with a stent-like primary supportstructure onto which a fabric-like material is attached, an embolicprotection device with a support frame onto which a blood filteringstructure is attached, a heart valve with a support ring onto whichvalve leaflets are attached, etc.

Nitinol material is preferable in such applications, more preferablymaterial which conforms to standard ASTM F2063 (Standard Specificationfor Wrought Nickel Titanium Shape Memory Alloys for Medical Devices andSurgical Implants). Nitinol can be shape-set, and is generally shape setfrom an initial smaller tube diameter to a larger expanded diameter,although cutting from a larger tube is also possible. The superelasticbehaviour of Nitinol allows device wrapping to a delivery configurationwithout significant permanent deformation, which facilitates deviceself-expansion once a delivery constraint is removed in-situ. There isno reason that the disclosure herein could not equally apply to medicaldevices comprising common medical grade metallic materials where selfexpansion is less of a requirement, such as stainless steel alloys,cobalt chromium alloys, tantalum, or any material suitable for medicaldevices or surgical implants. Furthermore, the disclosure could apply tostructures comprising bio-absorbable polymer materials such asPoly-L-lactic acid (PLLA), polyglycolic acid (PGA), poly (D,L-lactide/glycolide) copolymer (PDLA), and polycaprolactone (PCL) orbioabsorbable metallic stents made from materials such as magnesium.

A laser cutting method of cutting the pattern is generally referred toin the disclosure. Laser cutting is the preferred method of processingdevices of this scale because of the fine tolerances that can beachieved and the ablation process minimises the heat affected zone ofthe material, in particular where higher frequency or ultra highfrequency lasers are used. The principle also applies to abrasivecutting methods such as water jet, or thermal cutting processes such asEDX, although precision and tolerance control is likely to be morechallenging with these methods.

The examples given in the drawings demonstrate how side-wall eyelets canbe incorporated in a device which is manufactured from a tubular pieceof material. The conventional method of making these parts involvesrotating the tube about its axis and translating it in the axialdirection. The proposed method introduces an additional translation inthe transverse direction to create the side-wall feature. This principleof operation can be extended to a device manufactured from sheetmaterial, in which case the conventional production method translatesthe device in the axial and transverse directions, and a an additionalrotational direction is introduced to cut the side-wall features.Additional out of plane deflection of a partially cut device mayfacilitate cutting parallel to the planar surface of the sheet material.

In the description of the processing techniques, the first cut generallyrefers to the cutting of the primary strut pattern using a conventionalprocess setup, and a second cut generally refers to the cutting of theside-wall feature such as a side-wall eyelet or strut thin section. Thesequence of the first cut and the second cut can be interchanged so thatthe side-wall features are cut prior to cutting the primary strutpattern.

FIG. 84 is a cross sectional view of elongate tube 9001, where elongatetube 9001 comprises outer surface 9002, inner surface 9003, inner lumen9005, and tube wall 9004.

FIG. 85 a is an isometric view of in-process clot retrieval device 9016in a partially processed state, and FIG. 85 b is the same in-processclot retrieval device in cross-sectional view. The same numbering systemis used in FIG. 84, FIGS. 85 a, and 85 b. These figures show aconventional laser processing method where a primary structure is formedfrom cut pathway 9006, which is created by rotating elongate tube 9001about tube central axis 9007 and/or simultaneously moving it along tubecentral axis 9007. Cut pathway 9006 generally penetrates tube wall 9004by entering tube outer surface 9002 and exiting tube inner surface 9003at inner lumen 9005.

In FIG. 85 b in-process clot retrieval device 9016 using a conventionalprocess method is shown with cut source 9010 substantially above tubecentral axis 9007 and cut source trajectory 9015 in alignment orsubstantially in alignment with Z-Axis 9009. Tube wall 9004 is cut usingcut source 9010, which follows cut trajectory 9015. Cut source 9010enters elongate tube 9001 through outer surface 9002 at cut entry point9011, removes material from tube wall 9004, exits through tube innersurface 9003 at cut exit point 9012, and terminates at tube inner lumen9005. Laser ablation is the preferred material removal method, althoughfine abrasion processes such as water jet cutting, or thermal processesmay also be used. The process creates first cut space 9013 whichcomprises first cut surface 9014 on both sides of the cut. Thetransverse axis 9008 in FIG. 85 b is substantially perpendicular to Zaxis 9009.

FIG. 86 is a cross section of an as-cut clot retrieval device afterlaser cutting with a conventional process, but before heat setting andexpansion. As-cut clot retrieval device 9051 comprises a series ofstruts 9055 separated by cut space 9056. The struts are uniformly spacedaround the circumference of the device and have an aspect ratio withgreater strut thickness than strut width, i.e. the dimension of strut9055 on outer surface 9052 is greater than its dimension of strut in theradial direction along first cut surface 5054. The illustration is byway example only, and struts may be spaced unevenly or in pairs or maycomprise more or less struts around the circumference, with an aspect of1, or biased in the circumferential direction. Device inner surface 9053is located at device inner lumen 9057.

FIG. 87 is an isometric view of a portion of expanded clot retrievaldevice 9101. Clot retrieval device 9101 is manufactured usingconventional techniques, i.e., the setup described in FIG. 85 b. Strutouter surface 9102 and strut inner surface 9103 correspond with tubeouter surface 9052 and tube inner surface 9053 of as-cut clot retrievaldevice 9051 in FIG. 86, but are now in an expanded state. Similarly,strut side wall 9104 corresponds with first cut surface 9054 in the ascut configuration. Strut-width-eyelets 9105 are on the outer strutsurface of the struts and extend in the radial direction.Strut-width-eyelets in this example have a circular profile, and couldequally have an oval profile, square or rectangular profile, or slotprofile, etc. The corners of the strut-width-eyelet is generally roundedby the laser process and subsequent electropolishing process, typicallyto at a radius of 0.010 mm-0.015 mm or greater. The strut-width-eyeletinner wall 9106 may be formed by a single laser cut, for example where abeam of circular cross section cuts a circular eyelet, or whereby thedevice moves relative to the laser beam to cut a desired path to producealternative slot shapes such as ovals, squares, etc. Thestrut-width-eyelet 9105 is fully cut through the strut of dimensionstrut thickness 910 t. The dimension of strut width 910 w increases atthe location or strut-width-eyelet in this example, but can remainconstant for smaller eyelets or wider struts. It is generally desirablethat the strut width 910 w at the location of the strut-width eyelet9105 is not significantly greater than half the outer radius of crown9107 to prevent strut-width-eyelet 9105 from adding to the devicewrapped profile.

FIG. 88 is a cross section view of in-process clot retrieval device 9151with a side-wall eyelet in partially manufactured. Cut source 9161 iscutting the novel side-wall feature using a second cut. In thisillustration the in-process clot retrieval device has two first cutspaces 9156. Each first cut extends radially from tube outer surface9152 through tube wall 9154, and exits at tube inner surface 9153 intotube inner lumen 9155. The first cut is formed using the typical setupdescribed earlier but not illustrated here where cut source 9161 and cutsource trajectory 9162 are substantially aligned with Z-axis 9159. InFIG. 88 the central axis 9160 in no longer coincident with cut sourcetrajectory 9162—the in-process clot retrieval device 9151 has beentranslated relative to the cut source 9161 as depicted by arrow 9163.The translation is in the direction of transverse axis 9158, which mayalso be achieved by moving the cut source, moving the work piece,redirecting the cut trajectory, or any combination thereof. Cut sourcetrajectory 9162 shown enters the space of in-process clot retrievaldevice 9151 through first cut space 9156, enters tube wall at second cutentry point 9165 on first cut surface 9157 and exits at second cut exitpoint 9166 on first cut surface 9157 where it terminates at or afterfirst cut space 9157. The second cut space 9167 may form an eyelet in astrut defined by second cut surface 9168. The resulting device featuresand benefits are described in more detail later. Still referring now toFIG. 88 and referring back to FIG. 85 b, it may be necessary to make aprocess adjustment when changing from a first cut to a second cut, asthe distance from cut entry point to cut source may change. This may beachieved by keeping the distance from cut entry point 9165 to cut source9161 substantially constant by moving the work part relative to the cutsource as depicted by z-displacement 9164. This may also be achieved byre-focusing the energy from cut-source so that the distance from the cutsource 9161 to the energy focal point substantially matches the distancefrom the cut source to second cut entry point 9165. In this illustrationfirst cut space 9156 is depicted as being wider than second cut space9167 but could be an equivalent width or of greater width than first cutspace 9156. In this example, first cut space is depicted as a void, butit could also contain off-cut material, sacrificial, or waste materialgenerated by one or multiple first cuts, which can be removed from thedevice at a later point in the manufacturing process.

FIG. 89 a is an isometric view of a portion of clot retrieval device9201. The device is shown in a developed view or flattened state.Side-wall eyelets 9204 are located in strut side wall 9207. Clotretrieval device 9201 is fully expanded and electropolished with anyexcess waste material that result from the laser processing step fullyremoved, for example material from inter strut space 9208.

FIG. 89 b is a cross sectional view of clot retrieval device 9201 in adelivery configuration, where the cross section is taken throughmultiple side-wall eyelets. The clot retrieval device 9201 in this caseis in a circular configuration for delivery or deployment. FIGS. 89 aand 89 b show the fully processed clot retrieval device that correspondswith in-process clot retrieval device 9151 in FIG. 88. Device outersurface 9202, device inner surface 9203, and the strut side wall 9207 inFIGS. 89 a and 89 b correspond to tube outer surface 9152, tube innersurface 9153, and first cut surface 9157 in FIG. 88. Similarly side-walleyelet 9204 and eyelet wall 9205 correspond with second cut space 9167and second cut surface 9168 respectively. Likewise cut space 9165corresponds to inter strut space 9208.

FIGS. 90 a and 90 b are isometric and cross section views respectivelyof a portion of clot retrieval device 9251. Clot retrieval device 9251is made using conventional laser processing techniques describedpreviously, and now has fibres 9256 attached to improve clot retrievaland fragment capture capability. In this embodiment, fibre first side9257 of fibre 9256 is threaded strut-width-eyelet 9254. Fibre 9256enters from device inner surface 9253 and fibre second side 9258 exitsstrut-width-eyelet 9254 at device outer surface 9252. The fibres extendto form a net-like structure with a plurality of cross-over points 9259.In this embodiment fibre second side 9258 extends out of strut 9260 pastouter surface 9252, which has the effect of increasing the deviceprofile by at least the diameter of the fibre 9256. Fibre 9256 is incontact with eyelet wall 9255.

FIGS. 91 a and 91 b are isometric and side views respectively of aportion of clot retrieval device 9264. Clot retrieval device 9264 has aplurality of side-wall eyelets 9262 through the strut side wall 9261,having fibres 9256 attached. In this embodiment, fibre first side 9257of fibre 9256 and fibre second side 9258 are both below device outersurface 9252. The fibres 9256 in this embodiment do not extend pastdevice outer surface 9252, and therefore do not add to device profile inthe expanded or delivery configuration.

The device performance, as discussed previously, is generally enhancedby reducing the profile of the device. In this embodiment, profile isnaturally reduced by threading the fibres through the side-wall eyelet9262 rather than extending them past the strut outer surface.Additionally, wrapping of the device is more efficient in thisembodiment as the fibres occupy the space inside the inner devicesurface, and at least part of fibre occupies the inter strut space 9263.

This has the advantage of reduced device profile in the deliveryconfiguration, and may also have the advantage of a more evenlydistributed or predictable contact with a vessel wall in the deployedconfiguration. During clot retrieval, a clot may at least partiallyoccupy the inter strut space, after a strut at least partially embedsthe clot. The amount of grip the device has on the clot will depend onthe amount of embedding, and also on the friction between the strut andthe clot. Configuring the eyelets through the strut side and theresulting protrusion of the fibre through the strut side wall mayadditionally increase the friction between the clot and the device,thereby improving device grip on the clot.

FIG. 91 c is an isometric view of a portion of clot retrieval device9280 comprising struts 9281 with eyelets 9282 passing through the sidewalls 9284 of the struts, and fibre 9283 passing through some or all ofsaid eyelets. This is a similar construction to that described inrelation to FIGS. 91 a and 91 b, and could be employed to create avariant of many of the clot retrieval devices disclosed in thisdocument, such as for example in FIGS. 52 b, 66, 70, 71, 72 and 73.Fibre 9283 can be used to significantly increase the scaffolding of aregion of the clot retrieval device without significantly impacting thestiffness, wrapped profile or deliverability of the device. Ascaffolding pattern could be created by using a single fibre whichcircumnavigates the device multiple times without ever crossing overitself, or the fibre may cross over and inter-twine with itself multipletimes, or multiple fibres may be employed. The fibre(s) may pass througheyelets as shown and may be further adhered with adhesive or byadditional loops or knots to prevent slippage during loading anddelivery through a microcatheter.

FIG. 92 a is a cross sectional view of in-process clot retrieval device9301 with tube outer surface 9302, tube inner surface 9303, tube wall9304, and tube inner lumen 9305. In this embodiment the process isconfigured to remove material from the outer surface of the tube orstrut to produce a thin section of strut. The centre of in-process clotretrieval device 9301 is offset from the cut source 9308 such that cutsource trajectory 9309 is substantially tangential with tube outer wall9302. The partially processed clot retrieval device has a strut 9311which is defined by two first cut spaces 9306 and two first cut surfaces9307, the tube outer surface 9302, and the tube inner surface 9303. Inthis embodiment, laser trajectory 9309 enters the space of in processclot retrieval device 9301 through first cut space 9306, and cuts awaypart of tube outer surface 9302 to form a second cut space 9310 andsecond cut surface 9312.

FIG. 92 b is an isometric view of part of clot retrieval device 9316,which corresponds to in-process clot retrieval device 9301 of FIG. 92 a.Strut 9311 has a strut thin section 9315 as a result of material removedat second cut space 9310 in FIG. 92 a, and device outer surface 9313comprises tube outer surface 9302 and second cut surface 9312. Deviceouter surface 9313 is shown having a step down in profile; the profileshown is given by way of example only. They advantages of a step inprofile include improved grip on the clot and the ability to tailor thestiffness of a strut at discrete points along the device. Controllingstrut thickness at very discrete points is desirable to optimise deviceradial strength, loading force, flexibility, kink resistance, or anyother of the characteristics which are influenced by strut dimensionsthat ultimately lead to improved device performance.

The material removed from strut 9311 of clot retrieval device 9316 maybe done as a single cut, where the width of cut source trajectory 9309matches the width of material removed. Alternatively, if beam dimensionis less than the width of strut thin section 9315, cut source trajectory9309 may form two second cut surfaces 9312 through strut 9311 and followa path of strut thin section 9315 profile to form waste material thatlater falls away from strut.

In FIG. 93 a, a cross sectional view of an in-process clot retrievaldevice 9301 is shown with tube outer surface 9302, tube inner surface9303, tube wall 9304, and tube inner lumen 9305. In this embodiment theprocess is configured to remove material from the inner surface of thetube or strut to produce a thin section of strut. The cut sourcetrajectory 9309 is essentially the same as that described above for FIG.92 a, but now the centre of in-process clot retrieval device 9301 isoffset from the cut source 9308 such that cut source trajectory 9309 islocated at tube inner wall 9304.

FIG. 93 b is an isometric view of a portion of clot retrieval device9316, which corresponds to in-process clot retrieval device 9301 of FIG.93 a. Strut 9311 has a strut thin section 9315 as a result of materialremoved in the location of second cut space 9310 in FIG. 93 a fromdevice inner surface 9303. Strut inner surface 9314 of clot retrievaldevice 9316 has a step down in profile and comprises tube inner surface9303 and second cut surface 9312; the profile shown is given by way ofexample only. The advantages of a reduced strut profile and step inprofile on the inner of the device include strut stiffness profiletailoring at discrete points along the device, and the accommodation ofincreased profiles along the shaft, e.g., at the location of a collar.

FIG. 94 is an isometric view of part of clot retrieval device 9316 withstrut thin section 9315 created by removing material from device innersurface 9314 and from device outer surface 9313. This configurationincludes the benefits of the embodiments described in FIGS. 92 a-93 bwith the addition benefit of symmetry and balance which may promotepreferential in-plane bending during device wrapping and deployment.

FIG. 95 is a cross sectional view of clot retrieval device 9351 wrappedto a delivery diameter. In this embodiment the struts 9357 are arrangedin strut-sets 9354 with inter strut space 9353 between struts 9357within strut-set 9354, and with inter strut-set space 9355 betweenstrut-sets. The struts and strut-sets are formed using traditionalprocessing techniques from a first cut. This embodiment is configured tofacilitate cutting a second cut space 9359 through the first cut surfaceof each strut within struts sets 9354 with a single cut sourcetrajectory 9356. In the illustrated example, a strut-set comprises twostruts, but further arrangements are possible where strut-set 9354comprise greater than two struts.

FIG. 96 is a cross section of clot retrieval device 9351. In thisembodiment struts 9357 are arranged in strut-sets 9354 where inter strutspace 9353 is substantially the same size as inter strut-set space 9355.In this embodiment, eyelet 9358 is cut in both struts of strut-set 9354by cut source trajectory 9356, which enters first strut 9361 throughouter surface 9352, exits first strut 9361 through first cut surface9360, enters second strut 9362 through first cut surface 9360, and exitssecond strut 9362 through outer surface 9352. This embodiment has theadvantage of orienting the eyelet so that it penetrates the device outersurface and the strut side wall in a direction that is neither normalnor tangential to the device surface. An attached fibre will protrudepast the device outer surface and form a substantially acute angle withthe surface of the device, which will improve profile relative toconventional processing methods, as well as reduce the sharpness of abend and therefore the bending stress on the fibre at the eyelet exitpoint. Additional configurations are possible where strut-set 9354comprise more than two struts and eyelets are cut all of the struts inthe strut-set simultaneously. Strut-sets comprising n struts, where n>2in this configuration will result in n−2 struts having eyelets entirelythrough the strut side wall.

FIG. 97 is an isometric view of a portion of clot retrieval device 9401.This has strut-width-eyelets 9402 cut using conventional methods,side-wall eyelets 9403 using the method disclosed herein, andcombination eyelets 9404 comprising a co-located strut-width eyelet anda side-wall eyelet. This embodiment has an advantage of providing twoindependent fibre anchor points at a single location on the strut, and afibre path can be chosen entirely below device outer surface 9405.

FIG. 98 a shows a developed view of the body section 9451 of outermember 3671 of FIG. 65 a. As previously described this member comprisesa pair of hinged backbones made up of a series of connected diamondshaped cells 9452. These two backbones are the primary means of forcetransmission from one end of the device to the other, as the hingepoints 9453 are the only points of contact between the middle segment3673 and the proximal and distal segments (3672 and 3674 respectively).This construction has a particular advantage in that it minimizes thetendency for the device to reduce in diameter when under tension andwhen placed in bends, as the distal crowns of the six-sided cells 9454are not connected to any adjacent cell of the device. Another importantadvantage of this backbone design is that the twin backbones willpreferentially self-align in line with the plane of bending when thedevice is pulled through tortuousity. A neurovascular mechanicalthrombectomy can often require a clot to be retracted around multipletight bends before it can be safely retracted into a guide catheter. Atwin backbone design with the backbones 180 degrees opposed ensures thatthe device never has more than 90 degrees to rotate in order to reachits preferred lowest energy state. A single backbone design may offer abenefit in terms of flexibility and force transmission, but may have torotate by up to 180 degrees in order to reach its preferred lowestenergy state. This rotation may cause dislodgement of and escape of anycaptured clot. Using greater than two backbones compromises the abilityof the device to hold its shape in bends as it is no longer possible forall of the backbones to be simultaneously aligned with the neutralbending axis.

FIG. 98 b shows a developed view of a section of an outer member of asimilar design to that shown in FIG. 9451. Four sided cells 9472 and sixsided cells 9478 are illustrated which are similar to cells 9452 and9454 of member 9451, but are formed from struts with a degree ofcurvature that provides specific benefits to the interaction of thedevice with the clot with which it is intended to engage. These benefitsare best illustrated in relation to cell 9478, whose distal facing struthas a concave region 9475, an inflexion pt 9476 and a convex region9477. Both the convex and concave regions provide a portion of the strutface that is more perpendicular to the line of retraction of the clot(and axis of the vessel—9473) than a straight strut between the same endpoints would be, thus providing an increase in the clot grip performanceover the straight strut design. Strut portions 9471 and 9476 terminateat crown 9479, and clot under which this cell has been deployed will beurged towards this crown as the device is retracted. Because of thecurvature of these strut portions the direction in which the clot isurged 9477 is at an angle to the axis 9473 of the vessel. Each of theclot engaging cells of the outer member can in this way be configured tourge the clot in directions at angles of up to approximately 45 degreesto the vessel axis 9473. This directional change means that more workmust be done in order for the clot to slip or move along the device thanwould be the case if the crowns were not angled away from the vesselaxis, which in turn means that the grip of the device on the clot isenhanced.

FIGS. 99 a-d show various views of a device of this invention whichincorporates many of the features disclosed elsewhere, but will bedescribed again for clarity. The device 9501 of FIG. 99 a may bedescribed here and elsewhere in this specification as a stent-basket orexpandable body or elongate basket or engaging basket and comprises anelongate member which may be described here and elsewhere in thisspecification as a shaft 9502, to the distal end of which is connectedan inner elongate member 9503 which may be described here and elsewherein this specification as an inner tube or flow tube or inner tubularmember or inner body or inner elongate body and an outer elongate member9504 which may be referred to elsewhere as a stent-basket outer or outermember or outer tubular member or outer body or outer elongate body. Adistal capture net 9505 is integrated into the distal end of the outermember, and a distal soft tip 9506 is appended to the distal end of thedevice. The device is self-expanding, and is collapsible so that it canbe advanced through a conventional small diameter microcatheter to bedelivered to a target site, whereupon it is deployed across a targetclot by retraction of the microcatheter. The elongate shaft extendsexternally of the patient so that a user can retrieve the stent-basketand captured clot by retracting the shaft, and a coil element 9508 ispositioned over the shaft's core wire adjacent its distal end. Thestent-basket construction comprising an inner tube and outer membercreates a reception space 9507 between inner and outer to receive thetarget clot. Housing the clot in this reception space rather thanpinning it to the wall of the vessel means that the clot is under lesscompression and can thus be retracted at a lower force. The inner tube9503 and distal capture net 9505 protect the distal vascular bed fromembolization by preventing the escape from the reception space offragments of the captured clot.

The inner tube 9503 is configured to expand to a significantly lesserdiameter than that of the outer member, and is preferably sized toexpand to a slightly lesser diameter than that of the smallest vessel inwhich the device is intended to be deployed. In this way the inner tubecan be provided with a sufficiently high radial force to ensure that itexpands and creates a flow lumen through the clot in which the device isdeployed, without this radial force being directly imparted to the wallof the vessel. The resultant flow lumen which is smaller than theoriginal unobstructed diameter of the vessel provides a controlled flowof oxygenated blood to the previously starved distal vascular bed. Thiscontrolled restoration of flow is safer and more desirable than a suddenrestoration of full flow and pressure, which could be harmful to thecompromised distal vascular bed, as discussed in more detail in relationto FIG. 108.

The dual tube and capture net design of this stent-basket device enablesthe inner and outer body members to be far better tailored to performspecific tasks than would be the case with a single tube design. Inparticular the outer member can be configured to allow as much aspossible of the clot to migrate through it into the internal receptionspace without fear of this clot occluding the flow through the lumen orescaping out the distal end. Thus the clot inlet openings in the outermember of this design are much larger than would otherwise be possible,which ensure that the clot flows into the reception space, which in turnallows the struts of the outer member to act on the clot in thedirection in which the device is being retracted, rather than radiallyoutward against the vessel wall. The role played by the inner tube inthe initial grip and dislodgement of the clot also frees up the outermember to focus on retaining hold of the captured clot during retractionthrough bends and past branch vessels. Maintaining good apposition withthe vessel wall is key to retaining this grip on the clot. The segmentedand hinged design of the outer member is specifically tailored toachieving this apposition in bends and in tension. A conventionalstent-like clot retrieval device will tend to collapse in diameter inbends because placing such a device in a bend places the outer surfacein tension. When outer member 9504 is retracted through a bend its outersurface cannot be placed in this type of tension because there is noconnecting member on the outside of the bend to transmit this tensionfrom one segment to the next. The only connecting members are hingeelements 9525, which are configured to self-align to the neutral axisand allow the device to easily articulate in the bend. Thus thestent-basket device is able to retain its expanded shape and retain theclot within its reception space. Each segment is also able to retaingood apposition to the vessel wall and act as a barrier to prevent thedistal migration of captured clot.

FIG. 99 b shows a side view of the inner tube 9503, which comprises anelongate tubular structure 9510, a proximal connector 9511, a proximalpartial collar 9512, a distal collar 9516, a distal spring section 9513and a distal radiopaque coil tip 9514. The elongate tubular structure9510 in the embodiment shown comprises a network of interconnectedstruts 9515 laser cut from a nitinol tube in a 4 cell pattern. Theentire inner tube structure shown (excluding the distal radiopaque coiltip) may be laser cut from a single microtube, said microtube preferablyhaving an outer diameter smaller than the inner diameter of thecollapsed outer member when said outer member is loaded in amicrocatheter. The opening angles of the cells of the inner tube areconfigured so that the change in length (or foreshortening) of the innertube as it moves from the collapsed to expanded configuration is similarto that of the outer member, thus facilitating a connection between thedistal ends of both inner and outer members. The spring section 9513 canextend at a low force under tension to accommodate any change in therelative positions of the distal ends of both members, such as may occurwhen the device is deployed in a vessel of diameter smaller than that ofthe outer member but greater than that of the inner tube. Furtherdetails on foreshortening and associated designs are discussed below inrelation to FIG. 106 a.

FIG. 99 c shows a side view of the outer member 9504 and FIG. 99 d showsa developed view of the body of this same member. The outer membercomprises proximal, mid and distal scaffolding segments 9521, 9522 and9523 respectively, which are connected by hinge elements 9525. A capturenet 9505 comprising radially inward projecting struts is integrated intothe distal end of the distal segment (which may be more clearly viewedin FIG. 99 f). Proximal arms 9526 connect the proximal segment to aproximal collar 9527. Inlet mouths 9528 are located between the outermember segments so that when the device is deployed within a clot thescaffolding sections exert an outward radial force on the clot whichurges it to flow into the unscaffolded inlet mouth regions and into thereception space (as described in more detail in relation to FIG. 83 b).

In one embodiment the struts of the scaffolding sections are providedwith a very low coefficient of friction (through polishing, hydrophiliccoating, PTFE coating, silicon lubricant or other such means) so thatthe clot can easily slide off these segments and through the inletmouths into the internal reception space.

This outer member 9504 is very similar to outer member 9451 of FIG. 98a, however in this design the twin backbones comprise both diamond cells9524 and straight struts 9525, which offers increased flexibility andreduced foreshortening upon expansion. This pair of hinged backbones arethe primary means of force transmission from one end of the device tothe other, as struts 9525 (which act as hinge elements) are the onlypoints of contact between the middle segment 9522 and the proximal anddistal segments (9521 and 9523 respectively). This construction has aparticular advantage in that it minimizes the tendency for the device toreduce in diameter when under tension and when placed in bends, as thedistal crowns of the six-sided cells are not connected to any adjacentcell of the device. Another important advantage of this backbone designis that the twin backbones will preferentially self-align in line withthe plane of bending when the device is pulled through tortuousity. Aneurovascular mechanical thrombectomy can often require a clot to beretracted around multiple tight bends before it can be safely retractedinto a guide catheter. A twin backbone design with the backbones 180degrees opposed ensures that the device never has more than 90 degreesto rotate in order to reach its preferred lowest energy state. A singlebackbone design may offer a benefit in terms of flexibility and forcetransmission, but may have to rotate by up to 180 degrees in order toreach its preferred lowest energy state. This rotation may causedislodgement of and escape of any captured clot. Using greater than twobackbones compromises the ability of the device to hold its shape inbends as it is no longer possible for all of the backbones to besimultaneously aligned with the neutral bending axis.

Hinge elements may be flexible struts as shown, or in another embodimentmay be shaped as per elements 3411 shown in FIG. 60 a to allow greaterarticulation with less induced strain.

In one embodiment the outer member is laser cut from a nitinol tubewhose outer diameter is smaller than that of the microcatheter throughwhich the device is to be delivered. This small tubing enables fullproximal and distal collars to be incorporated into one monolithicstructure, and helps to ensure that the device is collapsible into a lowprofile microcatheter. In another embodiment the outer member is cutfrom a tube whose diameter is larger than that of the microcatheterthrough which the device is to be delivered. Cutting the outer memberfrom such a large diameter tubing can have several benefits. If themember is cut from a tube of diameter equal to the desired expandeddiameter of the member, then an expansion and heat setting process maynot be required, saving manufacturing time and cost and increasingyield. Another benefit may be seen in the collapsed shape of the struts,in that they are more likely to collapse into a less smooth and regularprofile than were they cut from a small tube. This irregularity canprovide fewer contact points to the inner lumen of a microcatheter forimproved deliverability, and can cause the struts to embed further intothe target clot upon deployment for superior grip.

In order to render the device visible under fluoroscopy the outer memberhas three marker bands 9531 located between adjacent crowns in itsdistal segment. These may comprise tabs of a radiopaque material such asgold, riveted into eyelets formed in the outer member. In otherembodiments alternative types of markers are employed such as shown inFIG. 43.

FIG. 99 e shows an isometric view of the region of the connectionbetween the proximal ends of the stent-basket inner and outer membersand the distal end of the device shaft. Shaft 9502 comprises a distalstep 9541 which acts as a mechanical stop to prevent the collars 9512and 9527 of the inner tubular member and outer member of thestent-basket from sliding off the end of the shaft in the event of afailure of whatever additional joining material (such as adhesive orsolder) may be present. Partial collar 9512 is held beneath collar 9527and causes collar 9527 to sit eccentrically on shaft 9502, which in turnmeans that it cannot slide past step 9541, even though this step has asmaller diameter than the inner diameter of collar 9527 (to facilitateassembly). Proximal strut 9511 connects the inner tubular member to itspartial collar 9512, and proximal struts 9526 connect the body of theouter member to its proximal collar 9527.

FIG. 99 f shows an isometric view of the distal end of the stent basket9504. This construction provides a means of connecting the distal end ofouter member 9504 and inner member 9503 which can accommodate a changein length of both members during either loading or expansion. The distalcone or capture net 9505 of outer member 9504 comprises multiple strutelements 9553, at least some of which terminate at collar 9552. Innermember 9503 comprises a collar 9516 to which is connected spring coil9513, which is in turn connected to an elongate strut 9517 (hiddenbeneath coil 9514 in this view). Elongate strut 9517 runs through tipcoil 9514 and they are joined at distal solder 9551, forming a round endto provide a smooth and atraumatic end to the device. Collar 9552 may beconnected to the distal end of spring element 9513, to the proximal endof elongate strut 9517, or to coil 9514. In another embodiment collar9552 is slidable on coil 9514 and distal solder 9551 may form a limitstop.

This construction has a number of benefits over both non-compliantlyconnected or unconnected distal end assemblies. If the inner and outermembers are designed to have matched lengths in both the collapsed andexpanded states (i.e. matched foreshortening) then there is likely to bea length mismatch in the partially expanded state which is likely tooccur when the device is deployed within a clot. In this situation theinner member will expand to a significant % of its fully expandeddiameter, and the outer member will expand to a similar diameter whichwill be significantly less than its fully expanded diameter. This willresult in less foreshortening of the outer than of the inner, and hencespring coil 9513 will be placed in tension. This spring element willthus absorb the length change and minimize the resultant tensile andcompressive forces applied to the inner and outer members themselvesrespectively. Adjustment of the spring constant and length can be usedto control the compressive force applied to the distal end of the outermember. This compressive force may assist in expanding the outer memberand adds to its radial force at the important stage of clot engagementand dislodgement. In addition this construction provides added degreesof freedom to the distal ends of the inner and outer members whichenables the device to flex and traverse tight bends at a lower forcethan were it rigidly connected.

FIG. 100 shows a side view of a preferred stent-basket of thisinvention. As has been previously explained it is intended that any ofthe stent-basket components described in this document (such as outermembers, inner tubes or capture nets for example) may be combined withany of the other components to form a range of stent-basket embodiments.The clot retrieval device 9601 comprises a preferred combination of manyof the components and features that have been described previously. Ithas an elongate shaft 9602 having a distal end that extends interior ofthe artery and a proximal end that extends exterior of the artery and ofthe body, an inner tubular member 9604 and an outer member 9605. Theinner and outer members are preferably made of a superelastic orpseudoelastic material such as Nitinol or another such alloy with a highrecoverable strain. Shaft 9602 may be a tapered wire shaft, and may bemade of stainless steel, MP35N, Nitinol or other material of a suitablyhigh modulus and tensile strength. Shaft 9602 has a sleeve 9616 adjacentits distal end and proximal of the outer member and inner tubularmember. This sleeve may be a metallic coil and may be formed fromstainless steel or from a more radiopaque material such as platinum orgold for example or an alloy of such a material. In another embodimentthis sleeve may be polymeric, and may be rendered radiopaque through theaddition of a filler material such as tungsten or barium sulphate. Shaft9602 may have integral collars or step features to assist the integrityof the joints between the distal end of the shaft and the proximal endsof the inner tubular member and the outer member. The proximal end ofthe outer member and proximal end of the inner tubular member maycomprise collars and said collars may comprise one or more elasticregions so that they can be assembled onto the shaft in the manner of asnap-fit joint. In other embodiments the proximal collars may be splitor may have other locating features to facilitate a strong joint to theshaft. In some embodiments one or both of these joints comprise asolder, braze or adhesive joint, while in another they may comprise aweld joint. In yet another embodiment one or both collars are rotatableon the shaft, and may be configured to slide along the axis of the shaftbetween limit stops. In yet other embodiments the inner member may bejoined to the outer member rather than directly to the shaft, or theouter member may be joined to the inner member, and a collar may not berequired to facilitate such a join.

Outer member 9605 comprises three expandable segments connected byhinged elements. Proximal struts 9610 are connected at their proximalends to collar 9603 and at their distal ends to a first expandablesegment 9606, which is in turn connected to a second expandable segment9607 by two connecting arms 9617, which comprise hinge elements 9612.Second expandable segment 9607, is in turn connected to a thirdexpandable segment 9608 by a similar pair of hinged connecting arms.

This segment and hinge construction provides a significant benefit inmaintaining good vessel wall apposition when the device is beingretracted through bends as described in greater detail in relation toFIG. 99 c. The outer member is configured to self-expand upon releasefrom a restraining sheath (such as a microcatheter) to a diameter largerthan that of the inner tubular member and functions in a manner similarto that described for outer member 8 of FIG. 1 a. The first and secondexpandable segments comprise a series of interconnected struts, withcertain struts terminating in crowns 9611 with no distal connectingelements, and other struts terminating in junction points such as 9620.The third expandable segment has a similar construction but terminatesin a densely scaffolded distal capture net to prevent the egress of clotor clot fragments that have entered said reception space. This capturenet comprises radially inward projecting struts 9613 containing eyelets9614 to which are attached one or more fibres 9615, and may be similarto that described in FIGS. 70 and 71.

The regions between the expandable segments comprise inlet mouths 9618through which clot may pass and enter the reception space defined by theregion between the inner and outer members. Upon deployment thescaffolded expandable segments expand and exert an outward radial forceon the clot, urging it to flow towards and through the unscaffoldedinlet mouth regions into a reception space 9619 between the outer andinner members.

Inner tubular member 9604 comprises a generally cylindrical section ofinterconnected struts, which is connected at its proximal end to shaft9602. In one embodiment the inner tubular member is connected to thedistal region of the outer member, and this connection may be acompliant connection to accommodate a certain amount of relative lengthchange between the inner and outer members as they go from a collapsedto expanded state and vice-versa. In other embodiments the inner tubularmember may not be connected to the distal end of the outer member atall, or may be constrained within the outer member without being fixedlyattached as disclosed elsewhere herein. In other embodiments the innertubular member may have a non-cylindrical cross-section, may benon-uniform in diameter, and may have tailored strut patterns to provideregions of differing radial force or flexibility. Inner members of suchdesigns are disclosed elsewhere in this document and it is intended tobe understood that these may be combined with any of the outer membersdisclosed herein, even though not all of these combinations may havebeen illustrated. The role of the inner member is described in moredetail in the detailed description pertaining to FIGS. 53 to 57.

FIG. 101 shows a developed view of the body 9651 of another stent basketouter member of this invention. As with other outer members disclosedelsewhere it is intended that this member could be combined with any ofthe inner members, capture nets, distal scaffolding designs and tipsshown elsewhere in this document to form a stent-basket. This outermember body comprises three distinct scaffolding regions 9652, 9653 and9654, spaced apart by large clot inlet mouths 9655 and 9656. Thescaffolding regions are connected by strut elements 9657 in such a waythat that the device effectively comprises a pair of backbones spacedapart 180 degrees in a similar fashion to that of previously describedmember 9451 of FIG. 98 a. Each backbone comprises both axial strutelements 9657 and cell elements 9658, which together provide a means offorce transmission from one end of the device to the other. The portionsof the strut elements that lie between the scaffolding zones act ashinges to allow the device to flex and bend without applying significantcompressive or tensile loads to the scaffolding sections. In this waythe scaffolding sections can retain their shape and maintain appositionwith the vessel wall during device retraction through tortuosity. The180 aligned backbone configuration minimizes the propensity of thedevice for excessive rotation or “flipping” as the device is retractedas described in relation to FIG. 98 a.

FIG. 102 shows a side view of the distal region of another stent-basketof this invention, in which a distal lumen scaffolding segment 9752 isjoined to a proximal segment 9751 by flexible joining elements 9755. Inthe embodiment shown the proximal crowns 9754 of the distal segment areconnected to the distal crowns 9753 of the proximal segment. In anotherembodiment the distal segment is connected to more proximal points onthe proximal segment such as junction points 9756, or struts projectingdistally from this point. The advantage of using flexible joiningelements, or of leaving crowns 9753 completely unconnected, is that moredegrees of freedom are provided to the distal end of the proximalsegment. This allows these distal crowns to better appose the vesselwall as the device is retracted, as they are not restrained from movingby the more distal segment of the device. Thus the distal end of theproximal segment can provide a better barrier to prevent the escape ofclot held by the proximal segment. In one embodiment flexible joiningelement 9755 comprises a fibre such as a monofilament or multifilamentof a polymer such as PET, PEN, UHMWPE, LCP or Aramid, or a metal such asStainless Steel, Nitinol, Tungsten or MP35N, Such high strengthmaterials allow the use of a very low profile fibre, thus ensuring thatthe overall collapsed profile of the device is not comprised. Ideallythe joining fibre should have a diameter of less than 0.050 mm, and mostpreferably it should be less than 0.030 mm.

FIG. 103 shows a side view of alternative flexible joining element tothe fibre described in relation to FIG. 102. Crowns 9781 and 9782 aresimilar to crowns 9753 and 9754 respectively of FIG. 102. Element 9783is a flexible link joining crowns 9781 and 9782, that can accommodatesignificant displacement of one crown relative to the other withouttransmitting a significant force from one to the other. In theembodiment shown the link and crowns are part of the one monolithicstructure, and might for example be laser machined as one part fromnitinol sheet or tubing.

FIG. 104 shows a side view of the distal end of a portion of anotherstent-basket in which significant degrees of freedom are provided todistal crowns 9801 while still providing a distal lumen scaffolding zone9802. This is made possible by forming the distal scaffolding zone fromstruts 9803 emanating from junction points 9804, rather than from crowns9801. Fibres 9808 are connected to struts 9803 to increase thescaffolding density in a similar fashion to that described in relationto FIG. 73 and elsewhere herein. Radiopaque markers 9807 are held ineyelets 9806, which are situated in low strain struts 9809 to minimizethe strain induced in the eyelets during device expansion and collapse,and hence ensure reliable marker retention strength. Tip 9805 isconnected to the distal end of the scaffolding zone and may comprise anyof the tip constructions described elsewhere, including a radiopaquecoil of platinum or similar material over a nitinol strut extending fromthe distal apex of connected struts 9803. An inner tubular member mayalso be provided and may be connected to the stent basket outer in anyof the manners describe elsewhere in this document.

FIG. 105 a shows a side view of a stent basket 9851 with an elongateshaft 9852, an inner flow tube 9853 and an outer member comprising twindiamond backbones 9854 and a distal scaffolding region 9855 with adistal tip 9856. This design means that the foreshortening of the innerand outer can be matched at all diameters rather than just at theircollapsed and expanded diameters, as has been described above. Thediamond backbones expand upon deployment to aid in engaging with anddislodging the clot from the vessel wall in conjunction with the innertube. As the device is retracted back into larger more proximal vesselsthe space between the backbones increases so that the captured clot canslip distally into the scaffolded distal cone.

FIG. 105 b shows a side view of a stent basket 9871 similar to thatshown in FIG. 105 a, but in this case additional ribs 9872 are providedbetween the outer member backbones. These ribs serve to hold thebackbones apart and apposed to the vessel wall, and define clot inletregions between adjacent ribs which allow clot to migrate into thereception space between outer and inner members. This design may also beemployed as a means to manufacture the design of FIG. 105 a. One way ofmanufacturing the design of FIG. 105 a from nitinol would be to cut thepart from a sheet or from a tube of diameter similar the fully expandeddiameter of the outer member. However a lower profile device may be moreeasily achieved using a small diameter tube closer to the collapseddevice diameter. The problem with cutting this part from a smalldiameter tube is that it must be heat set at an expanded diameter, andexpanding the diamond backbone would require expanding each cellindividually with the aid of expansion pins or similar. By adding theribs the part may easily be expanded by simply placing it onto acylindrical mandrel. The ribs may then be simply cut away prior topolishing to leave a rib-free design as per FIG. 105 a.

FIG. 105 c shows a side view of a stent basket 9881 similar to thatshown in FIG. 105 b, but in this case ribs 9882 have floatingdisconnected ends 9883. As described above, this design could bemanufactured with a connecting element between strut ends 9883, whichwould be removed post heat setting but prior to electropolishing. Theadvantage of these floating ribs is that they can easily be deflected toallow clot to enter the reception space between outer member and innertube, but once clot is within said reception space the ribs provide anobstacle to inhibit the clot from leaving the reception space.

Means of connecting the distal ends of the inner tube and outer memberare disclosed in FIGS. 106 and 107. These means may be used as analternative to the matched foreshortening designs described above, asthey do accommodate relative movement of the two members, or they may beused in conjunction with a matched foreshortening approach.

The principles of foreshortening described in relation to FIG. 33 mayalso be applied to match the foreshortening of the inner and outerelements of the stent baskets disclosed herein, so that their lengthsremain similar throughout the range of diameters to which they mayexpand. Matching the foreshortening minimizes the relative movement ofthe distal ends of the inner and outer members and facilitates thecreation of a connection between the two at their distal ends. Aconnection may be advantageous to control the position of the inner flowtube within the outer member of the stent basket. However it is not asimple matter to match the lengths of these two members over the fullrange of diameters. This is because the inner flow tube is designed toexpand to a smaller diameter than the outer member. Thus the inner flowtube may be fully expanded and fully foreshortened at a diameter of 1.5mm for example, while the outer member which may have a fully expandeddiameter of 5 mm has only foreshortened by a small amount at a diameterof 1.5 mm. One way of overcoming this problem is to design the outermember so that it foreshortens to the same degree as the inner member atthe fully expanded diameter of the inner member, but does not undergoany further foreshortening as it continues to expand from that diameterto its own fully expanded diameter. This unusual foreshorteningbehaviour can be achieved using the two stage radial force designsdescribed in relation to FIG. 48. Another way to achieve thisforeshortening behaviour is to use diamond backbone designs such asshown in FIG. 65 or 98 or 99 and provide the backbone with a strongeropening force than the rest of the member. In this way the backbone canbe configured with the same opening angle as the inner member, and canbe configured so that it is fully expanded at approximately the samediameter as that of the inner member. Once the backbone has fullyexpanded the further expansion of the scaffolding sections will haveminimal effect on foreshortening.

FIG. 106 a shows a side view of the distal end of a stent basket of thisinvention. The construction illustrated shows a means of connecting thedistal end of an outer member 9905 and an inner member 9901 which canaccommodate a change in length of both members during either loading orexpansion. Outer member 9905 comprises multiple strut elements 9911, atleast some of which terminate at collar 9906, which is in turn connectedto tip coil 9907, which terminates at distal collar 9908. Inner member9901 comprises multiple strut elements 9910, at least some of whichterminate at collar 9903, which is in turn connected to spring coil9902, which is in turn connected to an elongate strut 9904. Elongatestrut 9904 runs through tip coil 9907 and is joined to the outer memberat distal collar 9908. Suitable methods of joining include soldering,adhesive bonding and laser welding. A distal round end 9909 is situatedat this joint to provide a smooth and atraumatic end to the device. Thisdistal end 9909 could be formed by a solder, such as tin/silver or goldbased, or an adhesive such as a light curing epoxy. A radiopaque element9912 may be fitted over elongate strut 9904 and under tip coil 9907 torender the tip visible under fluoroscopy, and may comprise a coil ofwire made from a radiopaque material such as platinum or similar, or maycomprise a tube of a polymer material loaded with a radiopaque fillersuch as tungsten or tantalum or barium sulphate for example.

This construction has a number of benefits over both non-compliantlyconnected or unconnected distal end assemblies. If the inner and outermembers are designed to have matched lengths in both the collapsed andexpanded states (i.e. matched foreshortening) then there is likely to bea length mismatch in the partially expanded state which is likely tooccur when the device is deployed within a clot. In this situation theinner member will expand to a significant % of its fully expandeddiameter, and the outer member will probably expand to a similardiameter which will be significantly less than its fully expandeddiameter. This will result in less foreshortening of the outer than ofthe inner, and hence spring coil 9902 will be placed in tension and tipcoil 9907 will be placed in compression. These spring elements thusabsorb the length change and minimize the resultant tensile andcompressive forces applied to the inner and outer members themselvesrespectively. Adjustment of the spring constants and lengths can be usedto control the compressive force applied to the distal end of the outermember. This compressive force assists in expanding the outer member andadds to its radial force at the important stage of clot engagement anddislodgement. In addition this construction provides added degrees offreedom to the distal ends of the inner and outer members which enablesthe device to flex and traverse tight bends at a lower force than wereit rigidly connected.

In another embodiment collar 9906 is not a fully circumferentialelement, but rather comprises a connection point between one or morestruts of outer member 9905 and tip coil 9907. In yet another embodimenttip coil 9907 and outer member 9905 are laser cut as one part from thesame piece of tubing. The tip coil may comprise a helical strut ofconstant width, or more preferably a helical strut whose width tapersfrom proximal to distal end of the tip in order to provide an atraumaticstiffness transition to the tip. The spacing between coils may be lessthan or greater than the strut width, with greater spacing allowinggreater compression capacity and hence greater potential for lengthchange accommodation.

In yet another embodiment elongate strut 9904 is connected to the outermember at collar 9906 and does not extend through the tip coil 9907. Inyet another embodiment radiopaque element 9912 is not included. In yetanother embodiment radiopaque element 9912 is not included and springcoil 9902 extends most or all of the length of tip coil 9907 so thatelongate strut 9904 is very short or completely absent. In yet anotherembodiment a separate radiopaque marker band is attached to the outerdiameter of the distal end of the tip coil.

FIG. 106 b shows an end view of the device of FIG. 91 a. Radiallyinwardly facing struts 9911 create a scaffold across the vessel lumen toprevent the downstream escape of clot material captured within thestent-basket. These struts may be rendered highly flexible andatraumatic by minimizing their width and thickness as described inrelation to FIG. 68 and FIG. 69, or by modifying their shape asdescribed in relation to FIG. 67, or by disconnecting their terminalends as described in relation to FIG. 66. In another embodimentadditional scaffolding may be applied without penalty to profile orflexibility by means of adding fibres, such as shown in FIG. 52 b andFIG. 73 and elsewhere herein.

FIG. 107 shows an isometric view of the distal end of another stentbasket of this invention. The construction illustrated shows a means ofconnecting the distal end of an outer member 9905 and an inner member9934 which can accommodate a change in length of both members duringeither loading or expansion. Outer member 9905 comprises multiple strutelements 9911, at least some of which terminate at collar 9906, which isin turn connected to tip coil 9907, which terminates at distal tip 9908.Inner member 9934 terminates at a distal collar 9933, which is slidableon wire 9931. Wire 9931 is connected to the outer member 9905 at distalcollar 9906 (or in another embodiment at distal tip 9908) and extendsproximally through the inner tubular member 9934. A stop 9932 isdisposed at the proximal end of wire 9931 to prevent collar 9933 fromdisengaging with the wire. In this way the distal end of the innermember is slidably restrained within the outer member, without anysignificant tensile or compressive loads being induced on either memberby any changes in length due to foreshortening.

FIG. 108 shows a graph of blood flow rate (vertical axis 9951) vs. clottype (horizontal axis 9952) for a vessel with an occlusive clot in whichan expandable thrombectomy device has been deployed. Curve 9953 showsthe performance of a dual tube device of this invention such as thatshown in FIG. 33 or FIG. 51 or elsewhere, and curve 9954 shows theperformance of a typical single tube self-expanding stent-like clotretriever such as that illustrated in FIG. 13. The horizontal axis 9952plots clot types ranging from soft (9955), though medium (9956) to firm(9957), where soft clots are defined as clots with a modulus in theregion of 0.026 MPa, medium clots are defined as clots with a modulus inthe region of 0.17 MPa, and firm clots are defined as clots with amodulus in the region of 0.63 MPa; said modulus values being defined asthe 0-45% compressive values described by Chueh et al in “MechanicalCharacterization of Thromboemboli in Acute Ischemic Stroke andLaboratory Embolus Analogues”, AJNR 2011.

The vertical axis plots blood flowrate through the lumen created by theexpansion of the thrombectomy device in the clot. Line 9958 on this axisdepicts a flowrate of approximately 10 cc/100 g of brain tissue/minute.A flowrate of any less than this level is likely to result in anirreversible infarct within minutes, so it is desirable that theflowrate restored upon deployment of a mechanical thrombectomy deviceexceeds this level by a significant margin. Line 9959 on the verticalaxis depicts a flowrate of approximately 60 cc/100 g of braintissue/minute, which is a normal flowrate for a cerebral artery in ahealthy adult. Although it is desirable that this level of blood flow beultimately restored, it is desirable to do so gradually rather thanabruptly, as the sudden restoration of high pressure and flow to avascular bed which has been starved of oxygen and nutrients for asignificant period may result in harmful or even fatal brainhaemorrhage. Therefore a device that can reliably restore blood flow tothe ischemic brain, but do so at a controlled level, would be highlydesirable. Typical stent-like clot retriever devices which areconstructed in a similar manner to a self-expanding stent have arelatively linear radial force vs. diameter curve. This curve istailored to meet the demands of adequately gripping the clot withoutadversely harming the vessel. Thus when deployed in a very soft clotthey will tend to expand to a diameter close to that of the vesselitself, compressing the clot against the vessel wall, and creating alarge flow lumen and corresponding high flowrate. When deployed in veryfirm clot they may not have sufficient radial force to compress the clotto any significant degree, and thus the flowrate restored may be verylow. Dual tube designs of this invention overcome this problem by virtueof the fact that the inner tubular member can be configured to have afully expanded diameter of less than the lumen of the target vessel toensure that excessive flow is not restored, and a high radial force atthis small diameter to ensure that firm clots can be adequatelydisplaced. Thus a dual tube device can restore a similar, controlledflowrate regardless of clot type, and can do so without exerting harmfulradial forces on the vessel wall. Line 9961 and 9960 depicts the lowerand upper levels of a desirable restored flowrate window. Flowrate 9961is preferably at least twice that of level 9958 in order to ensure thatadequate oxygen and nutrients are provided to prevent further celldeath. Flowrate 9960 is preferably at least 40% lower than that of level9959 in order to ensure that the suddenly restored flowrate and pressuredo not harm the vascular bed.

It will be apparent from the foregoing description that, whileparticular embodiments of the present invention have been illustratedand described, various modifications can be made without parting fromthe spirit and scope of the invention. Accordingly, it is not intendedthat the present invention be limited and should be defined only inaccordance with the appended claims and their equivalents.

1. A clot retrieval device for removing occlusive clot from a blood vessel, the device comprising: an inner elongate body having a collapsed delivery configuration and an expanded deployed configuration; an outer elongate body at least partially overlying the inner elongate body; the outer elongate body being expandable relative to the inner elongate body to a radial extent which is greater than the radial extent of the inner body in the deployed configuration.
 2. A device as claimed in claim 1 comprising an elongate member having a proximal end and a distal end, the inner elongate body being connected to the elongate member adjacent to the distal end thereof, the inner elongate body being expandable relative to the elongate member.
 3. A device as claimed in claim 2 wherein the outer elongate body is connected to the elongate member adjacent to the distal end thereof, the outer elongate body being expandable relative to the elongate member.
 4. A device as claimed in claim 2 wherein the proximal end of the elongate member is adapted to extend exterior of the patient.
 5. A device as claimed in claim 1 wherein, in the expanded configuration, the outer elongate body is radially spaced-apart from the inner elongate body to define therebetween an interior reception space and wherein the outer elongate body has at least one opening to receive a clot.
 6. A device as claimed in claim 5 wherein the outer elongate body has an outer clot engaging region which is adapted, on engagement with clot, to urge clot towards the opening and into the interior reception space.
 7. A device as claimed in claim 5 wherein the outer elongate body comprises a plurality of clot-receiving openings.
 8. A device as claimed in claim 6 wherein the outer elongate body comprises a plurality of clot engaging regions.
 9. A device as claimed in claim 1 wherein the inner elongate body is generally tubular.
 10. A device as claimed in claim 1 wherein the inner elongate body comprises a non-circular cross-section.
 11. A device as claimed in claim 1 wherein the outer surface of the inner elongate body has a greater surface roughness than the outer surface of the outer elongate body.
 12. A device as claimed in claim 1 wherein the outer elongate body is generally tubular.
 13. A device as claimed in claim 1 wherein the outer elongate body comprises at least two segments which are longitudinally spaced-apart.
 14. A device as claimed in claim 13 at least two of said segments are connected by members comprising hinge elements.
 15. A device as claimed in claim 13 wherein at least one segment is movable relative to another segment.
 16. A device as claimed in claim 13 comprising linkages between the segments.
 17. A device as claimed in claim 16 wherein the linkages are adapted for controlled movement between the segments.
 18. A device as claimed in claim 1 comprising a distal capture net for trapping clot material.
 19. A device as claimed in claim 18 wherein the capture net is connected to the outer elongate body or the inner elongate body.
 20. A device as claimed in claim 18 wherein the capture net is mounted to or provided by a distal segment of either the outer elongate body and/or the inner elongate body.
 21. A device as claimed in claim 18 wherein the capture net is mounted to a distal portion of the elongate member.
 22. A device as claimed in claim 18 wherein the capture net comprises a plurality of radially inwardly projecting strut elements.
 23. A device as claimed in claim 18 wherein the capture net comprises one or more fibers.
 24. A device as claimed in claim 23 wherein the device comprises a plurality of fibre attachment eyelets to which said fibers are attached.
 25. A device as claimed in claim 2 wherein the elongate member comprises an assembly of at least one elongate wire and at least one elongate tubular member.
 26. A device as claimed in claim 25 wherein said elongate tubular member comprises a coil.
 27. A device as claimed in claim 25 wherein the elongate wire is slidably movable relative to the elongate tubular member.
 28. A device as claimed in claim 27 wherein movement of the elongate wire relative to the elongate tubular member effects movement of the outer elongate body relative to the inner elongate body and/or a distal capture net.
 29. A device as claimed in claim 1 wherein the outer elongate body comprises a plurality of struts, each strut having a vessel contacting surface, an inner surface, a proximally facing surface and a distally facing surface, said proximally facing surface comprising at least one protrusion.
 30. A device as claimed in claim 1 wherein the inner elongate body comprises a braided structure.
 31. A device as claimed in claim 2 wherein the inner and/or outer elongate bodies are slidably attached to a distal region of the elongate member, such that movement of the elongate member can be effected without resultant movement of the inner and/or outer elongate bodies.
 32. A device as claimed in claim 1 wherein the distal ends of the inner and outer elongate bodies are connected to one another.
 33. A device as claimed in claim 32 wherein the distal ends of the inner and outer elongate bodies are connected to one another by a compliant element.
 34. A device as claimed in claim 33 wherein the compliant element comprises a spring.
 35. A clot retrieval device for removing occlusive clot from a blood vessel of a patient, the device comprising: an elongate body which is expandable within a clot; the elongate body having an outer clot engaging regions and openings into an interior space defined by the elongate body; the clot engaging regions being adapted, on engagement with clot to urge the clot towards the openings and into the interior reception space.
 36. A device as claimed in claim 35 further comprising an elongate member having a proximal end and a distal end, the distal end of said elongate member being connected to the elongate body, and the proximal end of said elongate member extending exterior of the patient.
 37. A device as claimed in claim 35 wherein the elongate body is an outer elongate body and the device also comprises an inner elongate body which is at least partially overlayed by the outer elongate body, the outer elongate body being expandable relative to the inner elongate body to a radial extent which is greater than the radial extent of the inner body in the deployed configuration.
 38. A device as claimed in claim 37 wherein the inner elongate body comprises a generally tubular structure of interconnected struts.
 39. A device as claimed in claim 37 wherein the outer elongate body comprises two or more segments, at least some of the segments being connected to an adjacent segment by at least one flexible connecting element.
 40. A device as claimed in claim 35 comprising a distal capture net.
 41. A device as claimed in claim 40 wherein the capture net comprises a plurality of radially inwardly projecting strut elements.
 42. A device as claimed in claim 40 wherein the capture net comprises one or more fibers.
 43. A device as claimed in claim 42 wherein the device comprises a plurality of fibre attachment eyelets to which said fibers are attached.
 44. A clot retrieval device for use in the treatment of a patient with an occluded blood vessel, the device comprising: an elongate shaft and a clot engaging structure, the clot engaging structure being connected to the distal end of the elongate shaft and the proximal end of the elongate shaft extending exterior of the patient, the clot engaging structure comprising an outer wall and an inner reception space, said outer wall comprising a plurality of scaffolding sections and a plurality of inlet sections, said sections configured to urge clot into the inner reception space.
 45. A device as claimed in claim 44 wherein the elongate body is an outer elongate body and the device also comprises an inner elongate body which is at least partially overlayed by the outer elongate body, the outer elongate body being expandable relative to the inner elongate body to a radial extent which is greater than the radial extent of the inner body in the deployed configuration.
 46. A device as claimed in claim 45 wherein the inner elongate body comprises a generally tubular structure of interconnected struts.
 47. A device as claimed in claim 45 wherein the outer elongate body comprises two or more segments, each segment connected to the adjacent segment by two or one flexible connecting elements.
 48. A device as claimed in claim 44 comprising a distal capture net.
 49. A device as claimed in claim 48 wherein the capture net comprises a plurality of radially inwardly projecting strut elements.
 50. A device as claimed in claim 48 wherein the capture net comprises one or more fibers.
 51. A device as claimed in claim 50 wherein the device comprises a plurality of fibre attachment eyelets to which said fibers are attached. 